MST device for attachment to an adhesive surface

ABSTRACT

A micro-systems technology (MST) device for attachment to an adhesive surface. The MST device has
         an attachment surface for abutting the adhesive surfaces,   a first fluid conduit connected to a first aperture in the attachment surface and,   a recess in the attachment surface adjacent the first aperture to hold adhesive displaced from between the attachment surface and the adhesive surface when the MST device is attached such that displaced adhesive does not block fluid flow in the first conduit.       

     By profiling the attachment surface so there is a recess next to the first aperture, there is less risk that adhesive will be squeezed into the conduit and impair fluid flow.

FIELD OF THE INVENTION

The present invention relates to micro-system technologies (MST) devicesand in particular MST devices that use or process fluids. Inkjetprintheads are a widely used example of such devices and the inventionwill be described with specific reference to its application as aprinthead.

CO-PENDING APPLICATIONS

The following applications have been filed by the Applicantsimultaneously with the present application:

11/305274 11/305273 11/305275 11/305152 11/305158The disclosures of these co-pending applications are incorporated hereinby reference.

CROSS REFERENCES TO RELATED APPLICATIONS

Various methods, systems and apparatus relating to the present inventionare disclosed in the following US Patents/ Patent Applications filed bythe applicant or assignee of the present invention:

6750901 6476863 6788336 7249108 6566858 6331946 6246970 6442525 734658609/505951 6374354 7246098 6816968 6757832 6334190 6745331 72491097197642 7093139 10/636263 10/636283 10/866608 7210038 7401223 10/94065310/942858 7364256 7258417 7293853 7328968 7270395 11/003404 11/0034197334864 7255419 7284819 7229148 7258416 7273263 7270393 6984017 73475267357477 11/003463 7364255 7357476 11/003614 7284820 7341328 72468757322669 11/293800 11/293802 11/293801 11/293808 11/293809 11/24667611/246677 11/246678 11/246679 11/246680 11/246681 11/246714 11/2467137399057 11/246671 11/246704 11/246710 11/246688 7399054 11/2467157367648 7370936 7401886 11/246708 7401887 7384119 7401888 73873587413281 10/922842 10/922848 6623101 6406129 6505916 6457809 65508956457812 7152962 6428133 7204941 7282164 10/815628 7278727 10/91337310/913374 7367665 7138391 7153956 10/913380 10/913379 10/913376 71220767148345 11/172816 11/172815 11/172814 10/407212 7252366 10/6830647360865 11/293832 11/293838 11/293825 11/293841 11/293799 11/29379611/293797 11/293798 6746105 11/246687 11/246718 7322681 11/24668611/246703 11/246691 11/246711 11/246690 11/246712 11/246717 74018907401910 11/246701 11/246702 11/246668 11/246697 11/246698 11/24669911/246675 11/246674 11/246667 7156508 7159972 7083271 7165834 70808947201469 7090336 7156489 7413283 10/760246 7083257 7258422 72554237219980 10/760253 10/760255 7367649 7118192 10/760194 7322672 70775057198354 7077504 10/760189 7198355 7401894 7322676 7152959 72139067178901 7222938 7108353 7104629 7303930 11/246672 7401405 11/24668311/246682 7246886 7128400 7108355 6991322 7287836 7118197 10/7287847364269 7077493 6962402 10/728803 7147308 10/728779 7118198 71687907172270 7229155 6830318 7195342 7175261 10/773183 7108356 711820210/773186 7134744 10/773185 7134743 7182439 7210768 10/773187 71347457156484 7118201 7111926 10/773184 7018021 7401901 11/060805 11/18801711/097308 11/097309 7246876 11/097299 11/097310 7377623 7328978 73348767147306 09/575197 7079712 6285945 7330974 6813039 6987506 70387976980318 6816274 7102772 7350236 6881045 6728000 7173722 708845909/575181 7068382 7062651 6789194 6789191 6644642 6502614 66229996669385 6549935 6987873 6727996 6591884 6439706 6760119 7295332 62903496428155 6785016 6870966 6822639 6737591 7055739 7233320 6830196 68327176957768 09/575172 7170499 7106888 7123239 10/727181 10/727162 73776087399043 7121639 7165824 7152942 10/727157 7181572 7096137 73025927278034 7188282 10/727159 10/727180 10/727179 10/727192 10/72727410/727164 10/727161 10/727198 10/727158 10/754536 10/754938 10/72716010/934720 7171323 7278697 7369270 6795215 7070098 7154638 68054196829289 6977751 6398332 6394573 6622923 6747760 6921144 10/8848817092112 7192106 11/039866 7173739 6986560 7008033 11/148237 72227807270391 7195328 7182422 7374266 10/854522 10/854488 7281330 10/8545037328956 10/854509 7188928 7093989 7377609 10/854495 10/854498 10/8545117390071 10/854525 10/854526 10/854516 7252353 10/854515 726741710/854505 10/854493 7275805 7314261 10/854490 7281777 7290852 10/85452810/854523 10/854527 10/754524 10/854520 10/854514 10/854519 10/85451310/854499 10/854501 7266661 7243193 10/854518 10/854517 10/9346287163345 11/293804 11/293840 11/293803 10/293803 11/293834 11/29383511/293836 11/293837 11/293792 11/293794 11/293839 11/293826 11/29382911/293830 11/293827 11/293828 7270494 11/293823 11/293824 11/29383111/293815 11/293819 11/293818 11/293817 11/293816 10/760254 10/7602107364263 7201468 7360868 10/760249 7234802 7303255 7287846 715651110/760264 7258432 7097291 10/760222 10/760248 7083273 7367647 737435510/760204 10/760205 10/760206 10/760267 10/760270 7198352 73642647303251 7201470 7121655 7293861 7232208 7328985 7344232 708327211/074764 11/014763 7331663 7360861 7328973 11/014760 7407262 73062527249822 11/014762 7311382 7360860 7364257 7390075 7350896 11/0147587384135 7331660 11/014738 11/014737 7322684 7322685 7311381 72704057303268 11/014735 7399072 7393076 11/014750 11/014749 7249833 11/01476911/014729 7331661 11/014733 7300140 7357492 7357493 11/014766 73809027284816 7284845 7255430 7390080 7329894 7350913 7322671 738091011/014717 11/014716 11/014732 7347534 11/097268 11/097185 736765011/293820 11/293813 11/293822 11/293812 7357496 11/293814 11/29379311/293842 11/293811 11/293807 11/293806 11/293805 11/293810The disclosures of these applications and patents are incorporatedherein by reference.

Some applications have been listed by their docket number. These will bereplaced when application numbers are known. The disclosures of theseapplications and patents are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Many MST devices use or process fluid from an external source. Forexample, MST pressure sensors, printheads or diagnostic ‘lab on a chip’type devices need to allow fluid into the MST structures within thedevice. If the fluid is fed to the MST device from a larger supportingstructure, then it is usually necessary to seal micron scale conduits inthe support to micron scale conduits in the MST device. Accuratelyaligning the MST device relative to the support and forming a reliablefluid seal is difficult and time consuming.

Inkjet printhead integrated circuits (ICs) are good examples of MSTdevices that have a number of sealed connections to ink supply conduits.In light of this, the present invention will be described withparticular reference to inkjet printhead ICs. However, it will beappreciated that the invention has much broader application than that ofinkjet printheads.

SUMMARY OF THE INVENTION

According the present invention provides a MST device for attachment toan adhesive surface, the MST device comprising:

an attachment surface for abutting the adhesive surface;

a first fluid conduit connected to a first aperture in the attachmentsurface; and,

a recess in the attachment surface adjacent the first aperture to holdadhesive displaced from between the attachment surface and the adhesivesurface when the MST device is attached such that displaced adhesivedoes not block fluid flow in the first conduit.

By profiling the attachment surface so there is a recess next to thefirst aperture, there is less risk that adhesive will be squeezed intothe conduit and impair fluid flow.

Preferably the MST device has an array of inlet apertures in theattachment face for connection to a plurality of first fluid conduits,the mounting face has an array of outlet apertures connected to aplurality of second fluid conduits and the attachment face furthercomprising an array of recesses interspersed with the array of inletapertures.

Preferably the array of inlet apertures is series of open channels inthe attachment surface.

Preferably the array of recesses is an arrangement of pits in theattachment surface.

Preferably the channels are more than 50 microns wide and each separatedby more than 50 microns of the attachment face.

Preferably the channels are about 80 microns wide and separated by about80 microns of attachment face.

Preferably the pits are more than 5 microns wide and more than 5 micronsdeep.

Preferably the adhesive is a thermosetting adhesive that cures at apredetermined temperature.

Preferably the thermosetting adhesive has a maximum curing temperatureof 150 degrees Celsius.

Preferably the thermosetting adhesive are is more than 12 microns thick.

Preferably the MST device is a printhead IC and the support structure isa liquid crystal polymer (LCP) moulding.

In a second aspect the present invention provides a method of producinga printhead for an inkjet printer with a print engine controller forcontrolling the printhead operation, the method comprising the steps of:

providing a printhead IC having an array of ink ejection nozzles formedon a substrate;

providing circuitry for electrical connection to the print enginecontroller;

providing a support member for supporting the printhead IC and thecircuitry within the printer;

providing a polymer film;

securing the polymer film to a surface of the support member by applyingheat and pressure for a predetermined time;

mounting the printhead IC and the circuitry to the support member viathe polymer film; and,

electrically connecting the circuitry to the printhead IC.

Preferably, the circuitry is a flex PCB with tracks of conductivematerial in layers of polyimide film, and the printhead IC and the flexPCB are simultaneously attached to the support member via the polymerfilm.

Preferably, the circuitry is a flex PCB with tracks of conductivematerial in layers of polyimide film, and the flex PCB is attached tothe polymer film after the printhead IC is attached.

Preferably, the flex PCB has an adhesive area for attachment to thepolymer film once the polymer film has cooled and hardened after theprinthead IC attachment process.

Preferably, the circuitry is tracks of conductive material laid withinthe polymer film.

Preferably, the support member has a plurality of ink feed conduits forestablishing fluid communication with at least one ink storagecompartment; and,

the polymer film is attached to the support member between the ink feedconduits and the printhead integrated circuits, the polymer film havingan array of apertures such that the ejection nozzles are in fluidcommunication with the ink feed conduits.

Preferably, the polymer film is more than 25 microns thick.

Preferably, the polymer film is about 50 microns thick.

Preferably, the array of apertures is an array of laser drilled holes inregistration with respective ends of the ink feed conduits.

Preferably, the polymer sealing film is a laminate with an adhesivelayer on both sides of a thermoplastic film.

Preferably, the thermoplastic film is a PET or polysulphone.

Preferably, the ink feed conduits are formed in a liquid crystal polymermicro molding.

In a third aspect the present invention provides a method of attaching aMST device to a support member with an adhesive film, the MST devicehaving an attachment face and a first fluid conduit connected to a firstaperture in the attachment face;

the support member having a mounting face and a second fluid conduitconnected to a second aperture in the mounting face; and, the polymerfilm has an opening for fluid communication between the first apertureand the second aperture, the method comprising the steps of:

forming the opening in the polymer film;

aligning the opening with at least part of the second aperture;

applying heat and pressure to attach the polymer film to the mountingface; and, positioning the MST device such that the opening is alignedwith at east part of the first aperture.

By forming any holes or openings in the polymer film before it isattached to the support member is far less time consuming than formingany openings after the film is attached to the mounting surface.Furthermore, as the openings are usually formed by laser drilling, thereis a significant risk that some of the underlying support member is alsoablated. This ablated material can lodge in the opening or fluid conduitto constrict or clog the fluid flow.

Preferably, the polymer film is a laminated film having a central webbetween two outer layers of thermosetting adhesive.

Preferably, the MST device has an array of inlet apertures in theattachment face connected to a plurality of first fluid conduits, theattachment face has an array of outlet apertures connected to aplurality of second fluid conduits and the laminated film has an arrayof openings for establishing fluid communication between correspondingapertures in the inlet and outlet arrays.

Preferably, the opening in the laminated film is laser drilled.

Preferably, the laminated film is drilled with a UV laser so as to notcure the thermosetting adhesive layers immediately adjacent the opening.

Preferably, the central web is a polyimide film.

Preferably, the polyimide film is more than 25 microns thick.

Preferably, the polyimide film about 50 microns thick.

Preferably, each of the thermosetting adhesive layers is more than 12microns thick.

Preferably, each of the thermosetting adhesive layers are about 25microns thick.

Preferably, the array of inlet apertures is a series of open channels inthe attachment face.

Preferably, the channels are more than 50 microns wide and spaced fromadjacent channels by more than 50 microns.

Preferably, the attachment face has recesses adjacent the channels tohold thermosetting adhesive displaced from between the attachment faceand polyimide layer.

Preferably, the laminated film is sandwiched between two protectiveliners, the liner on the support member side of the laminated film beingremoved after laser drilling the opening but before the attachment ofthe support structure and the protective liner on the MST device side isremoved prior to attaching the MST device.

Preferably, the protective liners are PET.

Preferably, the thermosetting adhesive layers are initially made tackywhen the laminated film is first attached to the support member and theMST device and subsequently heated to their curing temperature.

Preferably, the thermosetting adhesive layers have different curingtemperatures so that the laminated film is cured to the support memberbefore the MST device is attached without the MST device sidethermosetting adhesive curing until after the MST device is attached.

Preferably, the opening is formed before the laminated film is attachedto the mounting surface of the support member.

Preferably, the MST devices are printhead ICs and the support structureis a liquid crystal polymer (LCP) molding.

Preferably, the laminated film is aligned with the fiducial markers onthe support structure with a vision system that calculates a point on orwithin one of the opening in the array of openings for each MST device.

In a fourth aspect the present invention provides laminated film formounting a MST device to a support structure for sealed fluidcommunication therebetween, the laminated film comprising:

a polymer carrier web between two thermosetting adhesive layers; and,

an opening formed in the film for establishing fluid communicationbetween a first fluid conduit in the MST device and a second fluidconduit in the support member.

Using a laminated film with thermosetting adhesive one each sideprovides a far more reliable seal than heated thermoplastic film. Thebond between the thermoplastic film and the MST device surface is proneto thermal fatigue and leakage or outright failure. A laminate with acentral carrier web and thermosetting adhesive can be drilled by a UVlaser and later heated to a known curing temperature so that theadhesive sets and forms a strong bond to the MST device surface.

Preferably, the MST device has an array of inlet apertures in theattachment face connected to a plurality of first fluid conduits, theattachment face has an array of outlet apertures connected to aplurality of second fluid conduits and the laminated film has an arrayof openings for establishing fluid communication between correspondingapertures in the inlet and outlet arrays.

Preferably, the opening is laser drilled.

Preferably, the thermosetting adhesive has a maximum curing temperatureof 150 degrees Celsius.

Preferably, the laser is a UV laser so as to not cure the thermosettingadhesive layers immediately adjacent the opening.

Preferably, the central web is a polyimide film.

Preferably, the polyimide film is more than 25 microns thick.

Preferably, the polyimide film about 50 microns thick.

Preferably, each of the thermosetting adhesive layers is more than 12microns thick.

Preferably, each of the thermosetting adhesive layers are about 25microns thick.

Preferably, the array of inlet apertures is a series of open channels inthe attachment face.

Preferably, the channels are more than 50 microns wide and spaced fromadjacent channels by more than 50 microns.

Preferably, the attachment face has recesses adjacent the channels tohold thermosetting adhesive displaced from between the attachment faceand polyimide layer.

In a further aspect there is provided laminated film further comprisingtwo protective liners on each outer surface, the liner on the supportmember side of the polymer film being removed after laser drilling theopening but before the attachment of the support structure and theprotective liner on the MST device side is removed prior to attachingthe MST device.

Preferably, the protective liners are PET.

Preferably, the thermosetting adhesive layers can be heated to atemperature less than the curing temperature to make them for initiallyattaching the support member and the MST device prior to subsequentheating to the curing temperature.

Preferably, the thermosetting adhesive layers have different curingtemperatures so that the polymer film is cured to the support memberbefore the MST device is attached without the MST device sidethermosetting adhesive curing until after the MST device is attached.

Preferably, the thermosetting adhesive layers have a viscosity between100 centiPoise and 10,000,000 centiPoise.

Preferably, the MST device is a printhead IC and the support structureis a liquid crystal polymer (LCP) molding.

Preferably, the support structure has at least one fiducial marker onthe mounting face and the array of openings is aligned with the array ofoutlet apertures using a vision system tracking a predetermined openingwithin the array of openings, relative to the at least one fiducialmarker.

In a fifth aspect the present invention provides a method of sealing anattachment face of a MST device to a mounting surface on a supportmember, the attachment face having an aperture connected to a firstfluid conduit, the attachment face having a second aperture connected toa second conduit, the method comprising the steps of:

applying a thermosetting adhesive to the mounting surface;

aligning the first aperture with at least part of the second aperture;

pressing the MST device and the mounting surface together; and,

curing the thermosetting adhesive; wherein,

the thermosetting adhesive has a viscosity of between 100 centiPoise and10,000,000 centiPoise.

Using a thermosetting adhesive instead of a thermoplastic adhesiveprovides a far more reliable seal. The bond between the thermoplasticadhesive and the MST device surface is prone to thermal fatigue andleakage or outright failure. A thermosetting adhesive can be heateduntil it is tacky for preliminary positioning of the MST device, andlater heated to a known curing temperature so that the adhesive sets andforms a strong chemical bond to the MST device surface. However, theviscosity of the adhesive must be low enough to allow the MST device toproperly embed into it, yet high enough that it does not extrude intothe conduits to the extent that the flow is blocked or overlyrestricted.

Preferably, the thermosetting adhesive is applied to the mountingsurface as a laminated film having a central web with a layer of thethermosetting adhesive on either side and an opening for fluidcommunication between the first aperture and the second aperture.

Preferably, the MST device has an array of inlet apertures in theattachment face connected to a plurality of first fluid conduits, theattachment face has an array of outlet apertures connected to aplurality of second fluid conduits and the laminated film has an arrayof openings for establishing fluid communication between correspondingapertures in the inlet and outlet arrays.

Preferably, the opening in the laminated film is laser drilled.

Preferably, the laminated film is drilled with a UV laser so as to notcure the thermosetting adhesive layers immediately adjacent the opening.

Preferably, the central web is a polyimide film.

Preferably, the polyimide film is more than 25 microns thick.

Preferably, the polyimide film about 50 microns thick.

Preferably, each of the thermosetting adhesive layers is more than 12microns thick.

Preferably, each of the thermosetting adhesive layers are about 25microns thick.

Preferably, the array of inlet apertures is a series of open channels inthe attachment face.

Preferably, the channels are more than 50 microns wide and spaced fromadjacent channels by more than 50 microns.

Preferably, the attachment face has recesses adjacent the channels tohold thermosetting adhesive displaced from between the attachment faceand polyimide layer.

Preferably, the laminated film is sandwiched between two protectiveliners, the liner on the support member side of the laminated film beingremoved after laser drilling the opening but before the attachment ofthe support structure and the protective liner on the MST device side isremoved prior to attaching the MST device.

Preferably, the protective liners are PET.

Preferably, the thermosetting adhesive layers are initially made tackywhen the laminated film is first attached to the support member and theMST device and subsequently heated to their curing temperature.

Preferably, the thermosetting adhesive layers have different curingtemperatures so that the laminated film is cured to the support memberbefore the MST device is attached without the MST device sidethermosetting adhesive curing until after the MST device is attached.

Preferably, the opening is formed before the laminated film is attachedto the mounting surface of the support member.

Preferably, the MST device is a printhead IC and the support structureis a liquid crystal polymer (LCP) molding.

Preferably, the support structure has at least one fiducial marker onthe mounting face and the array of openings is aligned with the array ofoutlet apertures using a vision system tracking a predetermined openingwithin the array of openings, relative to the at least one fiducialmarker.

In a sixth aspect the present invention provides a method of attachingMST devices to a support member via an adhesive film, the MST deviceseach having an attachment face with a first aperture and the supportmember having a mounting surface with second apertures corresponding toeach of the first apertures respectively and a fiducial marker for eachof the MST devices respectively, and the adhesive film having aplurality of openings, the method comprising the steps of:

positioning the adhesive film using the fiducial marker and thecorresponding opening such that the openings register with at least partof the second apertures in the mounting surface;

applying the adhesive film to the mounting surface;

positioning each of the MST devices relative to the respective openings;and,

attaching the MST devices with heat and pressure such that the openingsestablish the respective first and second apertures.

Instead of putting fiducial markers on both the film and the supportmember for alignment, the vision system use the fluid openingsthemselves. This is far more direct and precise as the fiducial markerson the film—usually very small holes—are prone to gross distortion andclosing over when the film is heated prior to attachment. The openingsare much larger features that suffer less distortion relative to theiroverall shape. Because the openings are large features, the visionsystem may need to determine a point on or within the opening, such athe centre, using any convenient technique for calculating this pointfor shapes that will have a degree of variance due to deformation.

Preferably, the adhesive film is a laminated film having a central webwith a layer of the thermosetting adhesive on either side and an openingfor fluid communication between the first aperture and the secondaperture.

Preferably, the MST device has an array of inlet apertures in theattachment face connected to a plurality of first fluid conduits, theattachment face has an array of outlet apertures connected to aplurality of second fluid conduits and the laminated film has an arrayof openings for establishing fluid communication between correspondingapertures in the inlet and outlet arrays.

Preferably, the opening in the laminated film is laser drilled.

Preferably, the laminated film is drilled with a UV laser so as to notcure the thermosetting adhesive layers immediately adjacent the opening.

Preferably, the central web is a polyimide film.

Preferably, the polyimide film is more than 25 microns thick.

Preferably, the polyimide film about 50 microns thick.

Preferably, each of the thermosetting adhesive layers is more than 12microns thick.

Preferably, each of the thermosetting adhesive layers are about 25microns thick.

Preferably, the array of inlet apertures is a series of open channels inthe attachment face.

Preferably, the channels are more than 50 microns wide and spaced fromadjacent channels by more than 50 microns.

Preferably, the attachment face has recesses adjacent the channels tohold thermosetting adhesive displaced from between the attachment faceand polyimide layer.

Preferably, the laminated film is sandwiched between two protectiveliners, the liner on the support member side of the laminated film beingremoved after laser drilling the opening but before the attachment ofthe support structure and the protective liner on the MST device side isremoved prior to attaching the MST device.

Preferably, the protective liners are PET.

Preferably, the thermosetting adhesive layers are initially made tackywhen the laminated film is first attached to the support member and theMST device and subsequently heated to their curing temperature.

Preferably, the thermosetting adhesive layers have different curingtemperatures so that the laminated film is cured to the support memberbefore the MST device is attached without the MST device sidethermosetting adhesive curing until after the MST device is attached.

Preferably, the opening is formed before the laminated film is attachedto the mounting surface of the support member.

Preferably, the MST devices are printhead ICs and the support structureis a liquid crystal polymer (LCP) molding.

Preferably, the laminated film is aligned with the fiducial markers onthe support structure with a vision system that calculates a point on orwithin one of the opening in the array of openings for each MST device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only, withreference to the preferred embodiments shown in the accompanyingfigures, in which:

FIG. 1 shows a front perspective view of a printer with paper in theinput tray and the collection tray extended;

FIG. 2 shows the printer unit of FIG. 1 (without paper in the input trayand with the collection tray retracted) with the casing open to exposethe interior;

FIG. 3 shows a schematic of document data flow in a printing systemaccording to one embodiment of the present invention;

FIG. 4 shows a more detailed schematic showing an architecture used inthe printing system of FIG. 3;

FIG. 5 shows a block diagram of an embodiment of the control electronicsas used in the printing system of FIG. 3;

FIG. 6 shows a perspective view of a cradle unit with open coverassembly and cartridge unit removed therefrom;

FIG. 7 shows the cradle unit of FIG. 6 with the cover assembly in itsclosed position;

FIG. 8 shows a front perspective view of the cartridge unit of FIG. 6;

FIG. 9 shows an exploded perspective view of the cartridge unit of FIG.8;

FIG. 10 shows an exploded front perspective view of the main body of thecartridge unit shown in FIG. 9;

FIG. 11 shows a bottom perspective view of the ink storage moduleassembly that locates in the main body shown in FIG. 9;

FIG. 12 shows an exploded perspective view of one of the ink storagemodules shown in FIG. 11;

FIG. 13 shows a bottom perspective view of an ink storage module shownin FIG. 12;

FIG. 14 shows a top perspective view of an ink storage module shown inFIG. 12;

FIG. 15 shows a top perspective view of the printhead assembly shown inFIG. 9;

FIG. 16 shows an exploded view of the printhead assembly shown in FIG.15;

FIG. 17 shows an inverted exploded view of the printhead assembly shownin FIG. 15;

FIG. 18A shows a cross-sectional end view of the printhead assembly ofFIG. 15;

FIG. 18B is a schematic sectional view of a known technique forattaching the printhead IC's to a support moulding;

FIGS. 18C-18E are schematic sectional views showing three embodiments ofthe printhead IC attached to the LCP moulding in accordance with oneaspect of the present invention;

FIG. 19 shows a magnified partial perspective view of the drop triangleend of a printhead integrated circuit module as shown in FIGS. 16 to 18;

FIG. 20 shows a magnified perspective view of the join between twoprinthead integrated circuit modules shown in FIGS. 16 to 19;

FIG. 21A shows an underside view of the printhead integrated circuitshown in FIG. 19;

FIG. 21B shows an underside view of the printhead integrated circuitshown in FIG. 19 with a series of recesses in its attachment face;

FIG. 22A shows a transparent top view of a printhead assembly of FIG. 15showing in particular, the ink conduits for supplying ink to theprinthead integrated circuits;

FIG. 22B is a partial enlargement of FIG. 28A;

FIG. 23 is a partial schematic section view of the attachment of theprinthead integrated circuit to the LCP moulding via the film;

FIG. 24 is a schematic partial section view of the laminate structure ofthe adhesive film prior to laser drilling;

FIG. 25 shows the laser drilling of the film pre-attachment;

FIG. 26 is a schematic partial section view of the laminate structure ofthe adhesive film during laser drilling;

FIG. 27 shows the attachment of the film to the LCP moulding;

FIG. 28 shows the attachment of the film to the printhead integratedcircuits;

FIG. 29 shows a vertical sectional view of a single nozzle for ejectingink, for use with the invention, in a quiescent state;

FIG. 30 shows a vertical sectional view of the nozzle of FIG. 35 duringan initial actuation phase;

FIG. 31 shows a vertical sectional view of the nozzle of FIG. 36 laterin the actuation phase;

FIG. 32 shows a perspective partial vertical sectional view of thenozzle of FIG. 35, at the actuation state shown in FIG. 31;

FIG. 33 shows a perspective vertical section of the nozzle of FIG. 29,with ink omitted;

FIG. 34 shows a vertical sectional view of the of the nozzle of FIG. 39;

FIG. 35 shows a perspective partial vertical sectional view of thenozzle of FIG. 35, at the actuation state shown in FIG. 36;

FIG. 36 shows a plan view of the nozzle of FIG. 35;

FIG. 37 shows a plan view of the nozzle of FIG. 35 with the lever armand movable nozzle removed for clarity;

FIG. 38 shows a perspective vertical sectional view of a part of aprinthead chip incorporating a plurality of the nozzle arrangements ofthe type shown in FIG. 35;

FIG. 39 shows a schematic cross-sectional view through an ink chamber ofa single nozzle for injecting ink of a bubble forming heater elementactuator type.

FIGS. 40A to 40C show the basic operational principles of a thermal bendactuator;

FIG. 41 shows a three dimensional view of a single ink jet nozzlearrangement constructed in accordance with FIG. 40;

FIG. 42 shows an array of the nozzle arrangements shown in FIG. 41;

FIG. 43 shows a schematic showing CMOS drive and control blocks for usewith the printer of the present invention;

FIG. 44 shows a schematic showing the relationship between nozzlecolumns and dot shift registers in the CMOS blocks of FIG. 43;

FIG. 45 shows a more detailed schematic showing a unit cell and itsrelationship to the nozzle columns and dot shift registers of FIG. 44;

FIG. 46 shows a circuit diagram showing logic for a single printernozzle in the printer of the present invention;

FIG. 47 shows a front perspective view of the maintenance assembly ofthe cartridge unit shown in FIG. 9;

FIG. 48 shows an exploded front perspective view of the maintenanceassembly of FIG. 47;

FIG. 49 shows an exploded front perspective view of the underside of themaintenance assembly of FIG. 47;

FIG. 50 shows a sectional view of the maintenance assembly operationallymounted to the cartridge unit of the present invention in a cappedstate;

FIGS. 51A and 51B show front and rear perspective views of the framestructure of the cradle unit according to one embodiment of the presentinvention;

FIGS. 52A-52B show left and right perspective views of the maintenancedrive assembly of the present invention remote from the frame structureof FIGS. 51A and 51B;

FIG. 53 shows a perspective view of the support bar assembly of FIGS.51A and 51B assembled to the PCB assembly;

FIG. 54 shows a perspective side view of the arms of the support barassembly of FIG. 53 connected to a spring element associated with thecover assembly;

FIGS. 55A-55C show various views of the cradle unit according to oneembodiment of the present invention;

FIGS. 56A and 56B show sectional side views of the cradle unit with thecover assembly in a closed and open position respectively;

FIGS. 57A and 57B show top and bottom perspective views of the inkrefill unit according to one embodiment of the present invention;

FIG. 57C shows an exploded view of the ink refill unit of FIGS. 57A and57B;

FIG. 58 shows a perspective view of the ink refill unit of FIGS. 57A and57B docked with the docking ports of the cover assembly;

FIG. 59 shows a plan view of the cradle with the cartridge inside andthe cover closed;

FIG. 60A shows a cross-sectional view of the ink refill unit and theprint engine along line A-A of FIG. 59;

FIG. 60B shows a cross-sectional view of the ink refill unit and theprint engine along line B-B of FIG. 59;

FIG. 60C shows a cross-sectional view of the ink refill unit in dockingposition with the print engine along line C-C of FIG. 59; and

FIG. 60D a cross-sectional view of the ink refill unit in dockingposition with the print engine along line D-D of FIG. 59.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a printer unit 2 embodying the present invention. Mediasupply tray 3 supports and supplies media 8 to be printed by the printengine (concealed within the printer casing). Printed sheets of media 8are fed from the print engine to a media output tray 4 for collection.User interface 5 is an LCD touch screen and enables a user to controlthe operation of the printer unit 2.

FIG. 2 shows the lid 7 of the printer unit 2 open to expose the printengine 1 positioned in the internal cavity 6. Picker mechanism 9 engagesthe media in the input tray 3 (not shown for clarity) and feedsindividual streets to the print engine 1. The print engine 1 includesmedia transport means that takes the individual sheets and feeds thempast a printhead assembly (described below) for printing and subsequentdelivery to the media output tray 4 (shown retracted).

FIG. 3 schematically shows how the printer unit 2 is arranged to printdocuments received from an external source, such as a computer system702, onto a print media, such as a sheet of paper. In this regard, theprinter unit 2 includes an electrical connection with the computersystem 702 to receive pre-processed data. In the particular situationshown, the external computer system 702 is programmed to perform varioussteps involved in printing a document, including receiving the document(step 703), buffering it (step 704) and rasterizing it (step 706), andthen compressing it (step 708) for transmission to the printer unit 2.

The printer unit 2 according to one embodiment of the present invention,receives the document from the external computer system 702 in the formof a compressed, multi-layer page image, wherein control electronics 766buffers the image (step 710), and then expands the image (step 712) forfurther processing. The expanded contone layer is dithered (step 714)and then the black layer from the expansion step is composited over thedithered contone layer (step 716). Coded data may also be rendered (step718) to form an additional layer, to be printed (if desired) using aninfrared ink that is substantially invisible to the human eye. Theblack, dithered contone and infrared layers are combined (step 720) toform a page that is supplied to a printhead for printing (step 722).

In this particular arrangement, the data associated with the document tobe printed is divided into a high-resolution bi-level mask layer fortext and line art and a medium-resolution contone color image layer forimages or background colors. Optionally, colored text can be supportedby the addition of a medium-to-high-resolution contone texture layer fortexturing text and line art with color data taken from an image or fromflat colors. The printing architecture generalises these contone layersby representing them in abstract “image” and “texture” layers which canrefer to either image data or flat color data. This division of datainto layers based on content follows the base mode Mixed Raster Content(MRC) mode as would be understood by a person skilled in the art. Likethe MRC base mode, the printing architecture makes compromises in somecases when data to be printed overlap. In particular, in one form alloverlaps are reduced to a 3-layer representation in a process (collisionresolution) embodying the compromises explicitly.

FIG. 4 sets out the print data processing by the print engine controller766. As mentioned previously, data is delivered to the printer unit 2 inthe form of a compressed, multi-layer page image with the pre-processingof the image performed by a mainly software-based computer system 702.In turn, the print engine controller 766 processes this data using amainly hardware-based system.

Upon receiving the data, a distributor 730 converts the data from aproprietary representation into a hardware-specific representation andensures that the data is sent to the correct hardware device whilstobserving any constraints or requirements on data transmission to thesedevices. The distributor 730 distributes the converted data to anappropriate one of a plurality of pipelines 732. The pipelines areidentical to each other, and in essence provide decompression, scalingand dot compositing functions to generate a set of printable dotoutputs.

Each pipeline 732 includes a buffer 734 for receiving the data. Acontone decompressor 736 decompresses the color contone planes, and amask decompressor decompresses the monotone (text) layer. Contone andmask scalers 740 and 742 scale the decompressed contone and mask planesrespectively, to take into account the size of the medium onto which thepage is to be printed.

The scaled contone planes are then dithered by ditherer 744. In oneform, a stochastic dispersed-dot dither is used. Unlike a clustered-dot(or amplitude-modulated) dither, a dispersed-dot (orfrequency-modulated) dither reproduces high spatial frequencies (i.e.image detail) almost to the limits of the dot resolution, whilesimultaneously reproducing lower spatial frequencies to their full colordepth, when spatially integrated by the eye. A stochastic dither matrixis carefully designed to be relatively free of objectionablelow-frequency patterns when tiled across the image. As such, its sizetypically exceeds the minimum size required to support a particularnumber of intensity levels (e.g. 16×16×8 bits for 257 intensity levels).

The dithered planes are then composited in a dot compositor 746 on adot-by-dot basis to provide dot data suitable for printing. This data isforwarded to data distribution and drive electronics 748, which in turndistributes the data to the correct nozzle actuators 750, which in turncause ink to be ejected from the correct nozzles 752 at the correct timein a manner which will be described in more detail later in thedescription.

As will be appreciated, the components employed within the print enginecontroller 766 to process the image for printing depend greatly upon themanner in which data is presented. In this regard it may be possible forthe print engine controller 766 to employ additional software and/orhardware components to perform more processing within the printer unit 2thus reducing the reliance upon the computer system 702. Alternatively,the print engine controller 766 may employ fewer software and/orhardware components to perform less processing thus relying upon thecomputer system 702 to process the image to a higher degree beforetransmitting the data to the printer unit 2.

FIG. 5 provides a block representation of the components necessary toperform the above mentioned tasks. In this arrangement, the hardwarepipelines 732 are embodied in a Small Office Home Office Printer EngineChip (SoPEC) 766. As shown, a SoPEC device consists of 3 distinctsubsystems: a Central Processing Unit (CPU) subsystem 771, a DynamicRandom Access Memory (DRAM) subsystem 772 and a Print Engine Pipeline(PEP) subsystem 773.

The CPU subsystem 771 includes a CPU 775 that controls and configuresall aspects of the other subsystems. It provides general support forinterfacing and synchronizing all elements of the print engine 1. Italso controls the low-speed communication to QA chips (described below).The CPU subsystem 771 also contains various peripherals to aid the CPU775, such as General Purpose Input Output (GPIO, which includes motorcontrol), an Interrupt Controller Unit (ICU), LSS Master and generaltimers. The Serial Communications Block (SCB) on the CPU subsystemprovides a full speed USB1.1 interface to the host as well as an InterSoPEC Interface (ISI) to other SoPEC devices (not shown).

The DRAM subsystem 772 accepts requests from the CPU, SerialCommunications Block (SCB) and blocks within the PEP subsystem. The DRAMsubsystem 772, and in particular the DRAM Interface Unit (DIU),arbitrates the various requests and determines which request should winaccess to the DRAM. The DIU arbitrates based on configured parameters,to allow sufficient access to DRAM for all requesters. The DIU alsohides the implementation specifics of the DRAM such as page size, numberof banks and refresh rates.

The Print Engine Pipeline (PEP) subsystem 773 accepts compressed pagesfrom DRAM and renders them to bi-level dots for a given print linedestined for a printhead interface (PHI) that communicates directly withthe printhead. The first stage of the page expansion pipeline is theContone Decoder Unit (CDU), Lossless Bi-level Decoder (LBD) and, whererequired, Tag Encoder (TE). The CDU expands the JPEG-compressed contone(typically CMYK) layers, the LBD expands the compressed bi-level layer(typically K), and the TE encodes any Netpage tags for later rendering(typically in IR or K ink), in the event that the printer unit 2 hasNetpage capabilities (see the cross referenced documents for a detailedexplanation of the Netpage system). The output from the first stage is aset of buffers: the Contone FIFO unit (CFU), the Spot FIFO Unit (SFU),and the Tag FIFO Unit (TFU). The CFU and SFU buffers are implemented inDRAM.

The second stage is the Halftone Compositor Unit (HCU), which dithersthe contone layer and composites position tags and the bi-level spotlayer over the resulting bi-level dithered layer.

A number of compositing options can be implemented, depending upon theprinthead with which the SoPEC device is used. Up to 6 channels ofbi-level data are produced from this stage, although not all channelsmay be present on the printhead. For example, the printhead may be CMYonly, with K pushed into the CMY channels and IR ignored. Alternatively,any encoded tags may be printed in K if IR ink is not available (or fortesting purposes).

In the third stage, a Dead Nozzle Compensator (DNC) compensates for deadnozzles in the printhead by color redundancy and error diffusing of deadnozzle data into surrounding dots.

The resultant bi-level 5 channel dot-data (typically CMYK, Infrared) isbuffered and written to a set of line buffers stored in DRAM via aDotline Writer Unit (DWU).

Finally, the dot-data is loaded back from DRAM, and passed to theprinthead interface via a dot FIFO. The dot FIFO accepts data from aLine Loader Unit (LLU) at the system clock rate (pclk), while thePrintHead Interface (PHI) removes data from the FIFO and sends it to theprinthead at a rate of 2/3 times the system clock rate.

In the preferred form, the DRAM is 2.5 Mbytes in size, of which about 2Mbytes are available for compressed page store data. A compressed pageis received in two or more bands, with a number of bands stored inmemory. As a band of the page is consumed by the PEP subsystem 773 forprinting, a new band can be downloaded. The new band may be for thecurrent page or the next page.

Using banding it is possible to begin printing a page before thecomplete compressed page is downloaded, but care must be taken to ensurethat data is always available for printing or a buffer under-run mayoccur.

The embedded USB 1.1 device accepts compressed page data and controlcommands from the host PC, and facilitates the data transfer to eitherthe DRAM (or to another SoPEC device in multi-SoPEC systems, asdescribed below).

Multiple SoPEC devices can be used in alternative embodiments, and canperform different functions depending upon the particularimplementation. For example, in some cases a SoPEC device can be usedsimply for its onboard DRAM, while another SoPEC device attends to thevarious decompression and formatting functions described above. This canreduce the chance of buffer under-run, which can happen in the eventthat the printer commences printing a page prior to all the data forthat page being received and the rest of the data is not received intime. Adding an extra SoPEC device for its memory buffering capabilitiesdoubles the amount of data that can be buffered, even if none of theother capabilities of the additional chip are utilized.

Each SoPEC system can have several quality assurance (QA) devicesdesigned to cooperate with each other to ensure the quality of theprinter mechanics, the quality of the ink supply so the printheadnozzles will not be damaged during prints, and the quality of thesoftware to ensure printheads and mechanics are not damaged.

Normally, each printing SoPEC will have an associated printer unit QA,which stores information relating to the printer unit attributes such asmaximum print speed. The cartridge unit may also contain a QA chip,which stores cartridge information such as the amount of ink remaining,and may also be configured to act as a ROM (effectively as an EEPROM)that stores printhead-specific information such as dead nozzle mappingand printhead characteristics. The refill unit may also contain a QAchip, which stores refill ink information such as the type/colour of theink and the amount of ink present for refilling. The CPU in the SoPECdevice can optionally load and run program code from a QA Chip thateffectively acts as a serial EEPROM. Finally, the CPU in the SoPECdevice runs a logical QA chip (i.e., a software QA chip).

Usually, all QA chips in the system are physically identical, with onlythe contents of flash memory differentiating one from the other.

Each SoPEC device has two LSS system buses that can communicate with QAdevices for system authentication and ink usage accounting. A largenumber of QA devices can be used per bus and their position in thesystem is unrestricted with the exception that printer QA and ink QAdevices should be on separate LSS busses.

In use, the logical QA communicates with the ink QA to determineremaining ink. The reply from the ink QA is authenticated with referenceto the printer QA. The verification from the printer QA is itselfauthenticated by the logical QA, thereby indirectly adding an additionalauthentication level to the reply from the ink QA.

Data passed between the QA chips is authenticated by way of digitalsignatures. In the preferred embodiment, HMAC-SHA1 authentication isused for data, and RSA is used for program code, although other schemescould be used instead.

As will be appreciated, the SoPEC device therefore controls the overalloperation of the print engine 1 and performs essential data processingtasks as well as synchronising and controlling the operation of theindividual components of the print engine 1 to facilitate print mediahandling, as will be discussed below.

Print Engine

The print engine 1 is shown in detail in FIGS. 6 and 7 and consists oftwo main parts: a cartridge unit 10 and a cradle unit 12.

The cartridge unit 10 is shaped and sized to be received within thecradle unit 12 and secured in position by a cover assembly 11 mounted tothe cradle unit. The cradle unit 12 is in turn configured to be fixedwithin the printer unit 2 to facilitate printing as discussed above.

FIG. 7 shows the print engine 1 in its assembled form with cartridgeunit 10 secured in the cradle unit 12 and cover assembly 11 closed. Theprint engine 1 controls various aspects associated with printing inresponse to user inputs from the user interface 5 of the printer unit 2.These aspects include transporting the media past the printhead in acontrolled manner and the controlled ejection of ink onto the surface ofthe passing media.

Cartridge Unit

The cartridge unit 10 is shown in detail in FIGS. 8 and 9. Withreference to the exploded view of FIG. 9, the cartridge unit 10generally consists of a main body 20, an ink storage module assembly 21,a printhead assembly 22 and a maintenance assembly 23.

Each of these parts are assembled together to form an integral unitwhich combines ink storage means together with the ink ejection means.Such an arrangement ensures that the ink is directly supplied to theprinthead assembly 22 for printing, as required, and should there be aneed to replace either or both of the ink storage or the printheadassembly, this can be readily done by replacing the entire cartridgeunit 10.

However, the operating life of the printhead is not limited by thesupply of ink. The top surface 42 of the cartridge unit 10 hasinterfaces 61 for docking with a refill supply of ink to replenish theink storage modules 45 when necessary. The ink refill unit and theprocess of docking with the cartridge are discussed in greater detailbelow. To further extend the life of the printhead, the cartridge unitcarries an integral printhead maintenance assembly 23 that caps, wipesand moistens the printhead. This assembly is also described in moredetail later.

Main Body

The main body 20 of the cartridge unit 10 is shown in more detail inFIG. 10 and comprises a substantially rectangular frame 25 having anopen top and an open longitudinally extending side wall. A pair of posts26 project from the underside of the frame at either end. These posts 26are provided to mount the maintenance assembly 23 to the main body 10,in a manner described below.

An ink outlet molding 27 has ink outlets (not shown) in its undersidecorresponding to each of the ink storage modules 45 to be housed in themain body 20. Each of the ink outlets has a pair of inwardly extendingsilicone rings seals. The rings seals are co-molded with the ink outletmolding 27 and seal against the ink inlets to the printhead assemblydescribed below. The ink outlet molding 27 is ultra sonically welded tothe underside of the rectangular frame 25.

Along one longitudinal wall of the frame 25 are a series of inkdownpipes 30. Each downpipe 30 has an O-ring seal 29 at its upper end toform a sealed connection with the ink outlet of respective ink storagemodules (described below). When the ink outlet molding 27 is welded tothe body 20, each ink downpipe 30 is in fluid communication withrespective ink outlets in the underside of the molding 27.

The air sleeve 31 is connected to a pressurized air source (not shown)and provides an air flow into the printhead assembly where it isdirected across the printhead nozzles to avoid paper dust clogging(discussed further below).

Ink filing ports 35 are formed in the lower parts of each ink downpipe30. These filling ports are for the initial charging of the ink storageassemblies 21 only. Any subsequent refilling of the ink storagesassemblies, uses the ink refill units described below. To assist theinitial filling process, a vacuum is applied to the air vents 41 in thetop surface 42 of the cartridge unit 10 (see FIG. 9). The air vents 41are connected to the interior of the ink bag in each ink storage module45 (described below). Ink is fed through the filling port 35 and drawnup the ink downpipe 30 into the ink storage volume. During the fillingprocess, the cartridge unit is tilted so that the air vents 41 are thehighest point in each of the respective ink bag, and filled until thevacuum draws ink through the air vent 41. This ensures that each ink bagis completely filled and purged of air. Skilled workers in this fieldwill appreciate that air bubbles entrained with the ink flow to theprinthead can harm the operation of the nozzles.

As shown in FIGS. 15 to 17, the lower member 65 is provided with aplurality of priming inlets 85 at one end thereof. Each of the priminginlets 85 communicate directly with one of the channels 67 and providean alternative, or additional means for priming the ink storage modules45 with ink prior to shipment and use.

When the ink storage modules are full, a polymer sealing ball 33 isinserted into the filling port 35 and the air vent 41.

A metal plate 34 mounts to the underside of the frame 25 and the outletmolding 30 to provide the cartridge unit 10 with structural rigidity. Itis snap locked into place by hooking the detents 38 into slots (notshown) in the back wall of the frame 25 and rotating the plate 34 untilthe line of barbed snap lock formations 32 clip into the outer line ofapertures 37.

The plate 34 has holes 39 to receive the ink outlets (not shown) thatproject from the lower surface of the outlet molding 27. The pressedmetal plate 34 also has a flange portion 40 projecting downwardly withrespect to the frame 25, which acts as a load bearing surface discussedin more detail below.

The ink storage assembly lid 21 of the cartridge unit 10 is shown indetail in FIGS. 11 to 14. The lid 21 is configured to mate with theframe 25 of the main body 20 to form an enclosed unit. As best shown inFIG. 11, the ink storage modules 45 are mounted to the underside of thelid 21 and extend into the individual cavities 36 provided by the mainbody 20 (see FIG. 10).

One of the ink storage modules 45 is shown in isolation in FIGS. 12, 13and 14. Ink bag 46 is made from a flexible, air impermeablethermoplastic film such as Mylar® which allows ink to be retainedtherein in a pressurised state. The flexible bag 46 can expand as it isfilled with ink and collapse as ink is consumed. This is discussed inmore detail later with reference to the refilling process shown in FIGS.60A to 60D.

The ink bag 46 extends between an upper plate member 47 and a lowerplate member 48. It is heat welded (or similar) to the plates 47 and 48for an air tight seal. The upper plate member 47 is arranged to receivea valve insert 49. The valve insert has an inlet valve 18 and an outletvalve 17. The valve insert 49 is positioned such that it can communicatedirectly with a port 51 formed in the top surface 42 to receive ink froman ink refill unit, as well as an outlet 52 to deliver ink to theprinthead assembly 22. As best shown in FIG. 14, the inlet valve 15receives the ink delivery needle of an ink refill unit (discussed later)through a slit positioned in the port 51 in the upper surface 42. Theinlet valve 18 is biased closed and opens when the refill unit(described below) docks with the cartridge unit 10.

Conversely, the outlet valve 18 is biased open and closes when therefill unit docks. A filter 215 covers the entrance to the outlet valvein the upper plate member 47. The filter is sized to remove solidcontaminants and air bubbles. As discussed above, compressible airbubbles can prevent a nozzle from operating.

The outlet valve connects to a conduit 52 in the underside of the lid 21which leads to the downpipe collar 216. When the ink storage assembly 21is placed into the main body 20, the collar 216 seals over the O-ringseal 29 on the end of the downpipe 30.

The upper plate 47 is fixed to the underside of the lid 21 to hold thevalve insert 49 in position. The lower plate 48 slides within the collar57 and the inside edges of the four struts 19 extending from theunderside of the lid 21. The plate 48 slides down the struts 19 as thebag 46 fills and expands. Conversely, it slides back towards the lid 21as the bag 21 empties. The length of the bag 46 limits the travel of thelower plate 48 before it reaches the retaining bar 55. A constant forcespring 54 extends between the retaining bar 55 and the recessed peg 59to bias the plate 48 towards the retaining bar 55. In turn, this biasesthe bag 46 to expand and thereby maintains the ink within the bag at anegative pressure. This avoids ink leakage from the printhead nozzles.

Bag Constrictor

Each ink storage module 45 has a bag constrictor 43 to re-establish thenegative pressure in the ink after each refilling operation. Theconstrictor 43 has a lower collar 57 that abuts the ends of the struts19 and is held in place by the retaining bar 55. The lower plate 48slides upwardly within lower collar 57 as the ink bag 46 empties. Fourbowed panels 58 extend upwardly from the lower collar 57 to an uppercollar 59. The panels 58 bow slightly inwards. The ink refill unit(described below) has four constrictor actuators. When the refill dockswith the cartridge unit, the constrictor actuators extend through theapertures 60 in the lid 21 to push the upper collar 59 towards the lowercollar 57. This causes the panels 58 to bow further inwards to press oneach side of the bag 46.

During refilling, the negative pressure in the ink bag 46 draws ink outof the refill unit. The negative pressure is created by the constantforce spring 54 biasing the lower plate 48 to wards the retainer bar 55.When the ink bag is full, the negative pressure disappears. Withoutnegative pressure in the ink bag 46, there is a risk of ink leakage fromthe nozzles. The negative pressure is re-established in the bag 46 whenthe refill unit is removed from the cartridge. As the four constrictoractuators retract through the apertures 60 in the lid 21, the bowedpanels 58 can push the upper collar 59 back towards the upper platemember 47. The panels 58 straighten so that they are not pressing on thesides of the bag 46 as much. This allows the bag 46 to bulge slightly,and as the inlet valve 18 is closed, the slight increase in bag volumerestores the negative pressure.

Printhead Assembly

The printhead assembly 22 is shown in more detail in FIGS. 15 to 18E,and is adapted to be attached to the underside of the main body 20 toreceive ink from the outlets molding 27 (see FIG. 10).

The printhead assembly 22 generally comprises an elongate upper member62 which is configured to extends beneath the main body 20, between theposts 26. A plurality of U-shaped clips 63 project from the upper member62. These pass through the recesses 37 provided in the rigid plate 34and become captured by lugs (not shown) formed in the main body 20 tosecure the printhead assembly 22.

The upper element 62 has a plurality of feed tubes 64 that are receivedwithin the outlets in the outlet molding 27 when the printhead assembly22 secures to the main body 20. The feed tubes 64 may be provided withan outer coating to guard against ink leakage.

The upper member 62 is made from a liquid crystal polymer (LCP) whichoffers a number of advantages. It can be molded so that its coefficientof thermal expansion (CTE) is similar to that of silicon. It will beappreciated that any significant difference in the CTE's of theprinthead integrated circuit 74 (discussed below) and the underlyingmoldings can cause the entire structure to bow. However, as the CTE ofLCP in the mold direction is much less than that in the non-molddirection (˜5 ppm/° C. compared to ˜20 ppm/° C.), care must be take toensure that the mold direction of the LCP moldings is unidirectionalwith the longitudinal extent of the printhead integrated circuit (IC)74. LCP also has a relatively high stiffness with a modulus that istypically 5 times that of ‘normal plastics’ such as polycarbonates,styrene, nylon, PET and polypropylene.

As best shown in FIG. 16, upper member 62 has an open channelconfiguration for receiving a lower member 65, which is bonded thereto,via an adhesive film 66. The lower member 65 is also made from an LCPand has a plurality of ink channels 67 formed along its length. Each ofthe ink channels 67 receive ink from one of the feed tubes 64, anddistribute the ink along the length of the printhead assembly 22. Thechannels are 1 mm wide and separated by 0.75 mm thick walls.

In the embodiment shown, the lower member 65 has five channels 67extending along its length. Each channel 67 receives ink from only oneof the five feed tubes 64, which in turn receives ink from one of theink storage modules 45 (see FIG. 10) to reduce the risk of mixingdifferent coloured inks. In this regard, adhesive film 66 also acts toseal the individual ink channels 67 to prevent cross channel mixing ofthe ink when the lower member 65 is assembled to the upper member 62.

In the bottom of each channel 67 are a series of equi-spaced holes 69(best seen in FIG. 17) to give five rows of holes 69 in the bottomsurface of the lower member 65. The middle row of holes 69 extends alongthe centre-line of the lower member 65, directly above the printhead IC74. As best seen in FIG. 22A, other rows of holes 69 on either side ofthe middle row need conduits 70 from each hole 69 to the centre so thatink can be fed to the printhead IC 74.

Referring to FIG. 18A, the printhead IC 74 is mounted to the undersideof the lower member 65 by a polymer sealing film 71. This film may be athermoplastic film such as a PET or Polysulphone film, or it may be inthe form of a therinoset film, such as those manufactured by ALTechnologies, Rogers Corporation or Ablestik (a subsidiary of NationStarch & Chemical Company). The polymer sealing film 71 presents anadhesive surface to mount and seal the printhead IC 74 to the undersideof the lower member 65. The sealing film 71 is a laminate with adhesivelayers on both sides of a central film, and laminated onto the undersideof the lower member 65. A particularly effective film is the Ablestik5205 SI and its structure is schematically shown in FIG. 24. The centralpolyimide web 222 is sandwiched between thermosetting adhesive layers220 and 224. The outer surfaces of the therinosetting adhesive layersare protected by PET liners 234 and 236. Mylar liners would also besuitable.

FIGS. 17, 22A and 22B, show the pattern of holes 72 laser drilledthrough the adhesive film 71 to coincide with the centrally disposed inkdelivery points (the middle row of holes 69 and the ends of the conduits70) for fluid communication between the printhead IC 74 and the channels67. FIGS. 25 and 26 schematically show the laser ablation process inmore detail. The laminated film 71 is fed from reel 240, past the laser238, and spooled onto reel 242. The laser is an excimer laser which usesUV light so that the thermosetting adhesive does not cure and harden. Ifthe adhesive hardens before the printhead IC 74 or the LCP moulding 65is attached, the seal may be compromised. Lasers that use longerwavelength light are more likely heat the adhesive above its curingtemperature. FIG. 26 shows a hole 72 drilled by the laser. The hole 72is a blind hole that terminates somewhere in the lower PET liner 236.Keeping the lower PET liner unbroken helps to keep contaminants out ofthe hole 72. The upper PET liner 234 collects some of the ablatedmaterial 244 removed from the hole 72 by the laser 238. Removing theliner immediately prior to attaching the film to the LCP moulding 65removes the ablated material 244 and any other detritus that may affectthe fluid seal.

FIG. 27 shows the attachment of the film 71 to the LCP moulding 65. Thelaser drilled film 71 is fed from the reel 242 to the LCP moulding 65.As the LCP moulding is a relatively long polymer moulding, it is notvery straight because of the inherent material weakness and the mouldingprocess. The moulding is gripped and held straight while the film isattached. A heated die 246 softens, but does not cure, the thermosettingadhesive so that it tacky. A vision system (not shown) aligns the film71 so that the appropriate holes 72 are at least partially inregistration with the ends of the ink conduits 70 etched into themoulding 65 (see FIG. 22B). This can be done using fiducial markings onboth the LCP moulding 65 and the film 71 or by using a vision systemthat references to predetermined features of both the moulding and/orthe film. This can be particularly useful for the film as the heatingprocess can often cause gross deformation or removal of the fiducialmarks (typically very small holes). If the vision system looks for oneor more predetermined holes 72 in the pattern of drilled holes, thealignment with the ink conduits 70 is more direct and accurate. Therelative deformation of the ink holes 72 is less because they arephysically much larger but the vision system can use a simple geometrictechnique to calculate a centre point, and then reference to that. ThePET liner 236 is peeled away before attachment, and reciprocating knives248 trim the film to size after attachment.

Drilling the holes in the film 71 before it is attached to the LCPmoulding is faster and more reliable than attaching the film to themoulding and then drilling. Drilling the film when it is attached to themoulding needs to be carefully controlled so that the hole extendcompletely through the film, but there is no overdrilling where a partof the underlying LCP is ablated by the laser. Ablated LCP easily lodgesin the holes 72 and causes flow blockages.

Turning to FIG. 28, the individual printhead ICs 74 are sequentiallyattached to the film 71. Heated die 260 holds each printhead IC 74 andattaches it to the film 71 once the vision system 262 has aligned itwith the previously attached printhead IC 74 and the holes 72. The LCPmoulding 65 is no longer held straight because the deviation fromexactly straight in the LCP moulding between one end of a printhead ICand the other is within acceptable tolerances. As discussed above, thevision system can reference to fiducials or it may reference topredetermined points on one or more of the holes 72 in the film 71. ThePET liner 234 is peeled away immediately prior to attachment to avoidcontamination. Again the die 260 heats the thermosetting adhesive 220(through the printhead IC 74) until it is tacky but not cured. Only whenthe series of printhead ICs 74 are stuck to the LCP moulding 65 via thefilm 71, is it finally cured by raising the temperature above the knowncuring temperature.

Alternatively, the film can use thermosetting adhesive layers withdifferent curing temperatures. By giving the layer 224 a lower curingtemperature than the layer 220, the film can be attached and cured tothe LCP moulding 65 before the printhead ICs 74 are attached and cured.Thermosetting adhesives provide a more reliable fluid seal than athermoplastic film. A thermoplastic film is heated and softened so theprinthead IC and LCP moulding can embed into the surface of the film.After the film cools, it attaches to the LCP with an essentiallymechanical bond. This is prone to fail and leak with prolonged thermalfatigue during operation. The thermosetting resin adhesive cures to forma strong bond with the surface of the printhead IC that withstands thedifferential thermal expansions within the printhead assembly.

FIG. 23 is a schematic partial section of the LCP moulding attached tothe printhead IC via the polymer film as shown in FIG. 22A. Ink flowsthrough the conduits 70 in the underside of the LCP moulding 65. Theopen channels 70 are sealed by the thermosetting adhesive layer 224 andthe inner ends of the channels 70 align with the holes 72 through thefilm. It is important to get the viscosity of the thermosetting adhesivelow enough to allow the printhead IC and the LCP moulding to adequatelyembed into the film surface, but no so low as to allow the adhesive tobulge into the fluid conduits to the extent that it causes a blockage orharmful constriction. However, a small amount of adhesive sagging or‘tenting’ (see 228, 230 and 232 of FIG. 23) into the fluid channels isnecessary for proper bonding and is not detrimental to ink flow.Therefore the adhesive viscosity range that provides a reliable sealwithout flow constriction will also depend on the dimensions andconfiguration of the apertures in the MST device and the support.Thermosetting adhesives with a viscosity between 100 centiPoise and10,000,000 centiPoise will seal micron-scale apertures of MST devices.Deeper and wider apertures can use adhesives with viscosities at thelower end of the range and smaller, shallower apertures need adhesiveswith a higher viscosity.

The printhead IC 74 has inlet apertures in the form of distributionchannels 77. These channels distribute ink to first conduits in the formof the inlets leading to each individual nozzle (not shown). Asdiscussed above, the distribution channels 77 form a sealed fluidconnection with second conduits in the form of holes 69 (see FIG. 22B)leading to the supply conduits 70. The holes 72 in the film 71 areoutlet apertures for ink in the conduits 70 flowing to the distributionchannels 77. While FIG. 23 is not to scale, it will be appreciated fromFIG. 22A that the distribution channels 77 are much smaller than thesupply conduits 70 in the LCP moulding 65. Hence the channels 77 aremore prone to clogging or constriction by adhesive displaced frombetween the carrier web 22 and upper face of the IC 74. To avoid this,recesses 264 can be formed in the attachment surface of the printhead ICto hold ink that would otherwise be squeezed into the channels 77. Asshown in FIG. 21B, these recesses may be a series of pits 264 about 10microns in diameter and 5 microns deep extending along both sides of the80 micron wide channels, spaced apart by 80 microns. The added textureand relief they give the attachment surface also aids the adhesion tothe film 71.

The thickness of the polymer sealing film 71 is critical to theeffectiveness of the ink seal it provides. FIGS. 2lA to 22B shows thereverse side of the printhead IC 74 which provides an attachment surfacethat contacts the adhesive surface provided by the polymer sealing film71 The polymer sealing film seals the etched channels 77 on the reverseside of the printhead IC 74, as well as the conduits 70 on the otherside of the film. However, as the film 71 seals across the open end ofthe conduits 70, it can also bulge or sag into the conduit. The sectionof film that sags into a conduit 70 runs across several of the etchedchannels 77 in the printhead IC 74. The sagging may cause a gap betweenthe walls separating each of the etched channels 77. Obviously, thisbreaches the seal and allows ink to leak out of the printhead IC 74 andor between etched channels 77.

To guard against this, the polymer sealing film 71 should be thickenough to account for any sagging into the conduits 70 while maintainingthe seal over the etched channels 77. The minimum thickness of thepolymer sealing film 71 will depend on:

the width of the conduit into which it sags;

the thickness of the adhesive layers in the film's laminate structure;

the ‘stiffness’ of the adhesive layer as the printhead IC 74 is beingpushed into it; and, the modulus of the central film material of thelaminate.

A polymer sealing film 71 thickness of 25 microns is adequate for theprinthead assembly 22 shown. However, increasing the thickness to 50,100 or even 200 microns will correspondingly increase the reliability ofthe seal provided. In the Ablestik laminate described above, thethermosetting layers are 25 microns thick and the polyimide carrier webis 50 microns thick. The PET or mylar liners are typically one 12microns thick.

Ink delivery inlets 73 are formed in the ‘front’ surface of a printheadIC 74. The inlets 73 supply ink to respective nozzles 801 (describedbelow with reference to FIGS. 35 to 36) positioned on the inlets. Theink must be delivered to the IC's so as to supply ink to each and everyindividual inlet 73. Accordingly, the inlets 73 within an individualprinthead IC 74 are physically grouped to reduce ink supply complexityand wiring complexity. They are also grouped logically to minimize powerconsumption and allow a variety of printing speeds.

Each printhead IC 74 is configured to receive and print five differentcolours of ink (C, M, Y, K and IR) and contains 1280 ink inlets percolour, with these nozzles being divided into even and odd nozzles (640each). Even and odd nozzles for each colour are provided on differentrows on the printhead IC 74 and are aligned vertically to perform true1600 dpi printing, meaning that nozzles 801 are arranged in 10 rows, asclearly shown in FIG. 19. The horizontal distance between two adjacentnozzles 801 on a single row is 31.75 microns, whilst the verticaldistance between rows of nozzles is based on the firing order of thenozzles, but rows are typically separated by an exact number of dotlines, plus a fraction of a dot line corresponding to the distance thepaper will move between row firing times. Also, the spacing of even andodd rows of nozzles for a given colour must be such that they can sharean ink channel, as will be described below.

Production Method

Various aspects of the production process discussed below with referenceto the schematic sectional views shown in FIGS. 18B-18E. One knowntechnique is shown in FIG. 18B. The polyimide film is removed from oneend of the flex PCB 79 to expose the conductive tracks 200. The tracks200 are spaced so that they are in registration with a line of bond padson the printhead IC 74. The tracks 74 are then directly connected to thebond pads. This technique is commonly known as ‘TAB bonding’ andrequires the flex PCB to be very accurate as well as a high degree ofprecision when aligning the flex PCB and the bond pads. Consequently,this can be a time consuming stage of the overall printhead productionprocess. It also requires the support molding 65 to have a steppedsection 204 to support the flex PCB 79 at the height of the printhead IC74. The stepped section 204 is an added design complexity.

This aspect of the present invention attaches both the printhead IC 74and the flex PCB 79 (or at least the conductive tracks 200) to thesupport molding 65 with the polymer film 71 before wiring 206 theconductive tracks 200 to the printhead IC 74. Attaching both theprinthead IC and the flex PCB to the support member with a polymer filmis a relatively quick and simple step as the highly precise alignment ofthe tracks and the bond pads is not critical. The subsequent wiring ofthe flex PCB to the bond pads can be done by automated equipment thatoptically locates the tracks and their corresponding bond pad on theprinthead IC. Small inaccuracies in the registration of the tracks andthe bond pads will not prevent the flex PCB from connecting to theprinthead IC, especially long IC's used in pagewidth printhead. As aresult the overall process is more time efficient and commerciallypractical.

FIG. 18C-18E show different options for the flex PCB and IC attachmentthat all use the same basic technique of the present invention. In FIG.18C, the flex PCB 79 is attached to the polymer film 71 after theprinthead IC 74 is attached. To do this, the flex PCB 79 has an adhesivearea 208 to attach to the polymer film 71 because the polymer film 71cools, hardens and loses its own adhesive qualities after the printheadIC 74 attachment process. With the flex PCB and the IC attached, thewire connections 206 are made and the protective encapsulator 202 added.

In FIG. 18D, the printhead IC 74 and the flex PCB 79 are simultaneouslyattached to the support molding 65 via the polymer film 71. This isquicker than attaching the flex and IC separately, but more complex.FIG. 18E shows a much simpler version where the conductive tracks areincorporated into the polymer film 71. As discussed above, the polymerfilm 71 is a laminate so the tracks can be positioned between thelayers. In this form, the polymer film effectively becomes the flex PCB.This option is quick and simple but the polymer film with incorporatedtracks is not an ‘off the shelf’ product.

For context, FIGS. 18C-18E show the upper member 62 and lower member 65of the LCP molding, the individual ink channels 67, the ink holes 69,the conduits 70 and the laser drilled holes 72 discussed in detailabove.

As alluded to previously, the present invention is related to page-widthprinting and as such the printhead ICs 74 are arranged to extendhorizontally across the width of the printhead assembly 22. To achievethis, individual printhead ICs 74 are linked together in abuttingarrangement across the surface of the polymer film 71, as shown in FIGS.16 and 17. The printhead IC's 74 may be attached to the polymer sealingfilm 71 by heating the IC's above the melting point of the adhesivelayer and then pressing them into the sealing film 71, or melting theadhesive layer of the film 71 under the IC with a laser before pressingit into the film. Another option is to both heat the IC (not above theadhesive melting point) and the adhesive layer, before pressing it intothe film 71.

As discussed above, the flex PCB can have an adhesive area forattachment to the polymer film 71, or a heated bar can press the flexonto the polymer film for a predetermine time.

Printhead Linking

The length of an individual printhead IC 74 is around 20-22 mm. To printan A4/US letter sized page, 11-12 individual printhead ICs 74 arecontiguously linked together. The number of individual printhead ICs 74may be varied to accommodate sheets of other widths.

The printhead ICs 74 may be linked together in a variety of ways. Oneparticular manner for linking the ICs 74 is shown in FIG. 20. In thisarrangement, the ICs 74 are shaped at their ends to link together toform a horizontal line of ICs, with no vertical offset betweenneighboring ICs. A sloping join is provided between the ICs havingsubstantially a 45° angle. The joining edge is not straight and has asawtooth profile to facilitate positioning, and the ICs 74 are intendedto be spaced about 11 microns apart, measured perpendicular to thejoining edge. In this arrangement, the left most ink inlets 73 to thenozzles on each row are dropped by 10 line pitches and arranged in atriangle configuration. This arrangement provides a degree of overlap ofnozzles at the join and maintains the pitch of the nozzles to ensurethat the drops of ink are delivered consistently along the printingzone. This arrangement also ensures that more silicon is provided at theedge of the IC 74 to ensure sufficient linkage. Whilst control of theoperation of the nozzles is performed by the SoPEc device (discussedlater in the description), compensation for the nozzles may be performedin the printhead, or may also be performed by the SoPEc device,depending on the storage requirements. In this regard it will beappreciated that the dropped triangle arrangement of nozzles disposed atone end of the IC 74 provides the minimum on-printhead storagerequirements. However where storage requirements are less critical,shapes other than a triangle can be used, for example, the dropped rowsmay take the fonn of a trapezoid.

The upper surface of the printhead ICs have a number of bond pads 75provided along an edge thereof which provide a means for receiving dataand or power to control the operation of the nozzles from the SoPECdevice. To aid in positioning the ICs 74 correctly on the surface of theadhesive layer 71 and aligning the ICs 74 such that they correctly alignwith the holes 72 fonned in the adhesive layer 71, fiducials 76 are alsoprovided on the surface of the ICs 74. The fiducials 76 are in the fonnof markers that are readily identifiable by appropriate positioningequipment to indicate the true position of the IC 74 with respect to aneighbouring IC and the surface of the adhesive layer 71, and arestrategically positioned at the edges of the ICs 74, and along thelength of the adhesive layer 71.

In order to receive the ink from the holes 72 formed in the polymersealing film 71 and to distribute the ink to the ink inlets 73, theunderside of each printhead IC 74 is configured as shown in FIG. 21. Anumber of etched channels 77 are provided, with each channel 77 in fluidcommunication with a pair of rows of inlets 73 dedicated to deliveringone particular colour or type of ink. The channels 77 are about 80microns wide, which is equivalent to the width of the holes 72 in thepolymer sealing film 71, and extend the length of the IC 74. Thechannels 77 are divided into sections by silicon walls 78. Each sectionsis directly supplied with ink, to reduce the flow path to the inlets 73and the likelihood of ink starvation to the individual nozzles 801. Inthis regard, each section feeds approximately 128 nozzles 801 via theirrespective inlets 73.

FIG. 22 B shows more clearly how the ink is fed to the etched channels77 formed in the underside of the ICs 74 for supply to the nozzle inlets73. As shown, holes 72 formed through the polymer sealing film 71 arealigned with one of the channels 77 at the point where the silicon wall78 separates the channel 77 into sections. The holes 72 are about 80microns in width which is substantially the same width of the channels77 such that one hole 72 supplies ink to two sections of the channel 77.It will be appreciated that this halves the density of holes 72 requiredin the polymer sealing film 71.

Following attachment and alignment of each of the printhead ICs 74 tothe surface of the polymer sealing film 71, a flex PCB 79 (see FIG. 18)is attached along an edge of the ICs 74 so that control signals andpower can be supplied to the bond pads 75 to control and operate thenozzles 801. As shown more clearly in FIG. 15, the flex PCB 79 extendsfrom the printhead assembly 22 and folds around the printhead assembly22.

The flex PCB 79 may also have a plurality of decoupling capacitors 81arranged along its length for controlling the power and data signalsreceived. As best shown in FIG. 16, the flex PCB 79 has a plurality ofelectrical contacts 180 formed along its length for receiving power andor data signals from the control circuitry of the cradle unit 12. Aplurality of holes 80 are also formed along the distal edge of the flexPCB 79 which provide a means for attaching the flex PCB to the flangeportion 40 of the rigid plate 34 of the main body 20. The manner inwhich the electrical contacts of the flex PCB 79 contact the power anddata contacts of the cradle unit 12 will be described later.

As shown in FIG. 18A, a media shield 82 protects the printhead ICs 74from damage which may occur due to contact with the passing media. Themedia shield 82 is attached to the upper member 62 upstream of theprinthead ICs 74 via an appropriate clip-lock arrangement or via anadhesive. When attached in this manner, the printhead ICs 74 sit belowthe surface of the media shield 82, out of the path of the passingmedia.

A space 83 is provided between the media shield 82 and the upper 62 andlower 65 members which can receive pressurized air from an aircompressor or the like. As this space 83 extends along the length of theprinthead assembly 22, compressed air can be supplied to the space 56from either end of the printhead assembly 22 and be evenly distributedalong the assembly. The inner surface of the media shield 82 is providedwith a series of fins 84 which define a plurality of air outlets evenlydistributed along the length of the media shield 82 through which thecompressed air travels and is directed across the printhead ICs 74 inthe direction of the media delivery. This arrangement acts to preventdust and other particulate matter carried with the media from settlingon the surface of the printhead ICs, which could cause blockage anddamage to the nozzles.

Ink Delivery Nozzles

One example of a type of ink delivery nozzle arrangement suitable forthe present invention, comprising a nozzle and corresponding actuator,will now be described with reference to FIGS. 35 to 38. FIG. 38 shows anarray of ink delivery nozzle arrangements 801 formed on a siliconsubstrate 8015. Each of the nozzle arrangements 801 are identical,however groups of nozzle arrangements 801 are arranged to be fed withdifferent colored inks or fixative. In this regard, the nozzlearrangements are arranged in rows and are staggered with respect to eachother, allowing closer spacing of ink dots during printing than would bepossible with a single row of nozzles. Such an arrangement makes itpossible to provide a high density of nozzles, for example, more than5000 nozzles arrayed in a plurality of staggered rows each having aninterspacing of about 32 microns between the nozzles in each row andabout 80 microns between the adjacent rows. The multiple rows also allowfor redundancy (if desired), thereby allowing for a predeterminedfailure rate per nozzle.

Each nozzle arrangement 801 is the product of an integrated circuitfabrication technique. In particular, the nozzle arrangement 801 definesa micro system technologies (MST) device.

For clarity and ease of description, the construction and operation of asingle nozzle arrangement 801 will be described with reference to FIGS.35 to 37.

The ink jet printhead integrated circuit 74 includes a silicon wafersubstrate 8015 having 0.35 micron 1 P4M 12 volt CMOS microprocessingelectronics is positioned thereon.

A silicon dioxide (or alternatively glass) layer 8017 is positioned onthe substrate 8015. The silicon dioxide layer 8017 defines CMOSdielectric layers. CMOS top-level metal defines a pair of alignedaluminium electrode contact layers 8030 positioned on the silicondioxide layer 8017. Both the silicon wafer substrate 8015 and thesilicon dioxide layer 8017 are etched to define an ink inlet channel8014 having a generally circular cross section (in plan). An aluminiumdiffusion barrier 8028 of CMOS metal 1, CMOS metal 2/3 and CMOS toplevel metal is positioned in the silicon dioxide layer 8017 about theink inlet channel 8014. The diffusion barrier 8028 serves to inhibit thediffusion of hydroxyl ions through CMOS oxide layers of the driveelectronics layer 8017.

A passivation layer in the form of a layer of silicon nitride 8031 ispositioned over the aluminium contact layers 8030 and the silicondioxide layer 8017. Each portion of the passivation layer 8031positioned over the contact layers 8030 has an opening 8032 definedtherein to provide access to the contacts 8030.

The nozzle arrangement 801 includes a nozzle chamber 8029 defined by anannular nozzle wall 8033, which terminates at an upper end in a nozzleroof 8034 and a radially inner nozzle rim 804 that is circular in plan.The ink inlet channel 8014 is in fluid communication with the nozzlechamber 8029. At a lower end of the nozzle wall, there is disposed amoving rim 8010, that includes a moving seal lip 8040. An encirclingwall 8038 surrounds the movable nozzle, and includes a stationary seallip 8039 that, when the nozzle is at rest as shown in FIG. 38, isadjacent the moving rim 8010. A fluidic seal 8011 is formed due to thesurface tension of ink trapped between the stationary seal lip 8039 andthe moving seal lip 8040. This prevents leakage of ink from the chamberwhilst providing a low resistance coupling between the encircling wall8038 and the nozzle wall 8033.

As best shown in FIG. 36, a plurality of radially extending recesses8035 is defined in the roof 8034 about the nozzle rim 804. The recesses8035 serve to contain radial ink flow as a result of ink escaping pastthe nozzle rim 804.

The nozzle wall 8033 forms part of a lever arrangement that is mountedto a carrier 8036 having a generally U-shaped profile with a base 8037attached to the layer 8031 of silicon nitride.

The lever arrangement also includes a lever arm 8018 that extends fromthe nozzle walls and incorporates a lateral stiffening beam 8022. Thelever arm 8018 is attached to a pair of passive beams 806, formed fromtitanium nitride (TiN) and positioned on either side of the nozzlearrangement, as best shown in FIGS. 38 and 37. The other ends of thepassive beams 806 are attached to the carrier 8036.

The lever arm 8018 is also attached to an actuator beam 807, which isformed from TiN. It will be noted that this attachment to the actuatorbeam is made at a point a small but critical distance higher than theattachments to the passive beam 806.

As best shown in FIGS. 35 and 35, the actuator beam 807 is substantiallyU-shaped in plan, defining a current path between the electrode 809 andan opposite electrode 8041. Each of the electrodes 809 and 8041 areelectrically connected to respective points in the contact layer 8030.As well as being electrically coupled via the contacts 809, the actuatorbeam is also mechanically anchored to anchor 808. The anchor 808 isconfigured to constrain motion of the actuator beam 807 to the left ofFIGS. 38 to 28 when the nozzle arrangement is in operation.

The TiN in the actuator beam 807 is conductive, but has a high enoughelectrical resistance that it undergoes self-heating when a current ispassed between the electrodes 809 and 8041. No current flows through thepassive beams 806, so they do not expand.

In use, the device at rest is filled with ink 8013 that defines ameniscus 803 under the influence of surface tension. The ink is retainedin the chamber 8029 by the meniscus, and will not generally leak out inthe absence of some other physical influence.

As shown in FIG. 36, to fire ink from the nozzle, a current is passedbetween the contacts 809 and 8041, passing through the actuator beam807. The self-heating of the beam 807 due to its resistance causes thebeam to expand. The dimensions and design of the actuator beam 807 meanthat the majority of the expansion in a horizontal direction withrespect to FIGS. 35 to 37. The expansion is constrained to the left bythe anchor 808, so the end of the actuator beam 807 adjacent the leverarm 8018 is impelled to the right.

The relative horizontal inflexibility of the passive beams 806 preventsthem from allowing much horizontal movement the lever arm 8018. However,the relative displacement of the attachment points of the passive beamsand actuator beam respectively to the lever arm causes a twistingmovement that causes the lever arm 8018 to move generally downwards. Themovement is effectively a pivoting or hinging motion. However, theabsence of a true pivot point means that the rotation is about a pivotregion defined by bending of the passive beams 806.

The downward movement (and slight rotation) of the lever arm 8018 isamplified by the distance of the nozzle wall 8033 from the passive beams806. The downward movement of the nozzle walls and roof causes apressure increase within the chamber 8029, causing the meniscus to bulgeas shown in FIG. 36. It will be noted that the surface tension of theink means the fluid seal 8011 is stretched by this motion withoutallowing ink to leak out.

As shown in FIG. 37, at the appropriate time, the drive current isstopped and the actuator beam 807 quickly cools and contracts. Thecontraction causes the lever arm to commence its return to the quiescentposition, which in turn causes a reduction in pressure in the chamber8029. The interplay of the momentum of the bulging ink and its inherentsurface tension, and the negative pressure caused by the upward movementof the nozzle chamber 8029 causes thinning, and ultimately snapping, ofthe bulging meniscus to define an ink drop 802 that continues upwardsuntil it contacts adjacent print media.

Immediately after the drop 802 detaches, meniscus 803 forms the concaveshape shown in FIG. 37. Surface tension causes the pressure in thechamber 8029 to remain relatively low until ink has been sucked upwardsthrough the inlet 8014, which returns the nozzle arrangement and the inkto the quiescent situation shown in FIG. 35.

Another type of printhead nozzle arrangement suitable for the presentinvention will now be described with reference to FIG. 33. Once again,for clarity and ease of description, the construction and operation of asingle nozzle arrangement 1001 will be described.

The nozzle arrangement 1001 is of a bubble forming heater elementactuator type which comprises a nozzle plate 1002 with a nozzle 1003therein, the nozzle having a nozzle rim 1004, and aperture 1005extending through the nozzle plate. The nozzle plate 1002 is plasmaetched from a silicon nitride structure which is deposited, by way ofchemical vapour deposition (CVD), over a sacrificial material which issubsequently etched.

The nozzle arrangement includes, with respect to each nozzle 1003, sidewalls 1006 on which the nozzle plate is supported, a chamber 1007defined by the walls and the nozzle plate 1002, a multi-layer substrate1008 and an inlet passage 1009 extending through the multi-layersubstrate to the far side (not shown) of the substrate. A looped,elongate heater element 1010 is suspended within the chamber 1007, sothat the element is in the form of a suspended beam. The nozzlearrangement as shown is a micro system technologies (MST) structure,which is formed by a lithographic process.

When the nozzle arrangement is in use, ink 1011 from a reservoir (notshown) enters the chamber 1007 via the inlet passage 1009, so that thechamber fills. Thereafter, the heater element 1010 is heated forsomewhat less than 1 micro second, so that the heating is in the form ofa thermal pulse. It will be appreciated that the heater element 1010 isin thermal contact with the ink 1011 in the chamber 1007 so that whenthe element is heated, this causes the generation of vapor bubbles inthe ink. Accordingly, the ink 1011 constitutes a bubble forming liquid.

The bubble 1012, once generated, causes an increase in pressure withinthe chamber 1007, which in turn causes the ejection of a drop 1016 ofthe ink 1011 through the nozzle 1003. The rim 1004 assists in directingthe drop 1016 as it is ejected, so as to minimize the chance of a dropmisdirection.

The reason that there is only one nozzle 1003 and chamber 1007 per inletpassage 1009 is so that the pressure wave generated within the chamber,on heating of the element 1010 and forming of a bubble 1012, does noteffect adjacent chambers and their corresponding nozzles.

The increase in pressure within the chamber 1007 not only pushes ink1011 out through the nozzle 1003, but also pushes some ink back throughthe inlet passage 1009. However, the inlet passage 1009 is approximately200 to 300 microns in length, and is only approximately 16 microns indiameter. Hence there is a substantial viscous drag. As a result, thepredominant effect of the pressure rise in the chamber 1007 is to forceink out through the nozzle 1003 as an ejected drop 1016, rather thanback through the inlet passage 1009.

As shown in FIG. 39, the ink drop 1016 is being ejected is shown duringits “necking phase” before the drop breaks off. At this stage, thebubble 1012 has already reached its maximum size and has then begun tocollapse towards the point of collapse 1017.

The collapsing of the bubble 1012 towards the point of collapse 1017causes some ink 1011 to be drawn from within the nozzle 1003 (from thesides 1018 of the drop), and some to be drawn from the inlet passage1009, towards the point of collapse. Most of the ink 1011 drawn in thismanner is drawn from the nozzle 1003, forming an annular neck 1019 atthe base of the drop 1016 prior to its breaking off.

The drop 1016 requires a certain amount of momentum to overcome surfacetension forces, in order to break off. As ink 1011 is drawn from thenozzle 1003 by the collapse of the bubble 1012, the diameter of the neck1019 reduces thereby reducing the amount of total surface tensionholding the drop, so that the momentum of the drop as it is ejected outof the nozzle is sufficient to allow the drop to break off.

When the drop 1016 breaks off, cavitation forces are caused as reflectedby the arrows 1020, as the bubble 1012 collapses to the point ofcollapse 1017. It will be noted that there are no solid surfaces in thevicinity of the point of collapse 1017 on which the cavitation can havean effect.

Yet another type of printhead nozzle arrangement suitable for thepresent invention will now be described with reference to FIGS. 34-36.This type typically provides an ink delivery nozzle arrangement having anozzle chamber containing ink and a thermal bend actuator connected to apaddle positioned within the chamber. The thermal actuator device isactuated so as to eject ink from the nozzle chamber. The preferredembodiment includes a particular thermal bend actuator which includes aseries of tapered portions for providing conductive heating of aconductive trace. The actuator is connected to the paddle via an armreceived through a slotted wall of the nozzle chamber. The actuator armhas a mating shape so as to mate substantially with the surfaces of theslot in the nozzle chamber wall.

Turning initially to FIGS. 34( a)-(c), there is provided schematicillustrations of the basic operation of a nozzle arrangement of thisembodiment. A nozzle chamber 501 is provided filled with ink 502 bymeans of an ink inlet channel 503 which can be etched through a wafersubstrate on which the nozzle chamber 501 rests. The nozzle chamber 501further includes an ink ejection port 504 around which an ink meniscusforms.

Inside the nozzle chamber 501 is a paddle type device 507 which isinterconnected to an actuator 508 through a slot in the wall of thenozzle chamber 501. The actuator 508 includes a heater means e.g. 509located adjacent to an end portion of a post 510. The post 510 is fixedto a substrate.

When it is desired to eject a drop from the nozzle chamber 501, asillustrated in FIG. 34( b), the heater means 509 is heated so as toundergo thermal expansion. Preferably, the heater means 509 itself orthe other portions of the actuator 508 are built from materials having ahigh bend efficiency where the bend efficiency is defined as:

${{bend}\mspace{14mu}{efficiency}} = \frac{{{Young}'}s\mspace{14mu}{Modulus} \times \left( {{Coefficient}\mspace{14mu}{of}\mspace{14mu}{thermal}\mspace{14mu}{Expansion}} \right)}{{Density} \times {Specific}\mspace{14mu}{Heat}\mspace{14mu}{Capacity}}$

A suitable material for the heater elements is a copper nickel alloywhich can be formed so as to bend a glass material.

The heater means 509 is ideally located adjacent the end portion of thepost 510 such that the effects of activation are magnified at the paddleend 507 such that small thermal expansions near the post 510 result inlarge movements of the paddle end.

The heater means 509 and consequential paddle movement causes a generalincrease in pressure around the ink meniscus 505 which expands, asillustrated in FIG. 34( b), in a rapid manner. The heater current ispulsed and ink is ejected out of the port 504 in addition to flowing infrom the ink channel 503.

Subsequently, the paddle 507 is deactivated to again return to itsquiescent position. The deactivation causes a general reflow of the inkinto the nozzle chamber. The forward momentum of the ink outside thenozzle rim and the corresponding backflow results in a general neckingand breaking off of the drop 512 which proceeds to the print media. Thecollapsed meniscus 505 results in a general sucking of ink into thenozzle chamber 502 via the ink flow channel 503. In time, the nozzlechamber 501 is refilled such that the position in FIG. 34( a) is againreached and the nozzle chamber is subsequently ready for the ejection ofanother drop of ink.

FIG. 35 illustrates a side perspective view of the nozzle arrangement.FIG. 36 illustrates sectional view through an array of nozzlearrangement of FIG. 35. In these figures, the numbering of elementspreviously introduced has been retained.

Firstly, the actuator 508 includes a series of tapered actuator unitse.g. 515 which comprise an upper glass portion (amorphous silicondioxide) 516 formed on top of a titanium nitride layer 517.Alternatively a copper nickel alloy layer (hereinafter calledcupronickel) can be utilized which will have a higher bend efficiency.

The titanium nitride layer 517 is in a tapered form and, as such,resistive heating takes place near an end portion of the post 510.Adjacent titanium nitride/glass portions 515 are interconnected at ablock portion 519 which also provides a mechanical structural supportfor the actuator 508.

The heater means 509 ideally includes a plurality of the taperedactuator unit 515 which are elongate and spaced apart such that, uponheating, the bending force exhibited along the axis of the actuator 508is maximized. Slots are defined between adjacent tapered units 515 andallow for slight differential operation of each actuator 508 withrespect to adjacent actuators 508.

The block portion 519 is interconnected to an arm 520. The arm 520 is inturn connected to the paddle 507 inside the nozzle chamber 501 by meansof a slot e.g. 522 formed in the side of the nozzle chamber 501. Theslot 522 is designed generally to mate with the surfaces of the arm 520so as to minimize opportunities for the outflow of ink around the arm520. The ink is held generally within the nozzle chamber 501 via surfacetension effects around the slot 522.

When it is desired to actuate the arm 520, a conductive current ispassed through the titanium nitride layer 517 within the block portion519 connecting to a lower CMOS layer 506 which provides the necessarypower and control circuitry for the nozzle arrangement. The conductivecurrent results in heating of the nitride layer 517 adjacent to the post510 which results in a general upward bending of the arm 20 andconsequential ejection of ink out of the nozzle 504. The ejected drop isprinted on a page in the usual manner for an inkjet printer aspreviously described.

An array of nozzle arrangements can be formed so as to create a singleprinthead. For example, in FIG. 36 there is illustrated a partlysectioned various array view which comprises multiple ink ejectionnozzle arrangements laid out in interleaved lines so as to form aprinthead array. Of course, different types of arrays can be formulatedincluding full color arrays etc.

The construction of the printhead system described can proceed utilizingstandard MST techniques through suitable modification of the steps asset out in U.S. Pat. No. 6,243,113 entitled “Image Creation Method andApparatus (IJ 41)” to the present applicant, the contents of which arefully incorporated by cross reference.

The integrated circuits 74 may be arranged to have between 5000 to100,000 of the above described ink delivery nozzles arranged along itssurface, depending upon the length of the integrated circuits and thedesired printing properties required. For example, for narrow media itmay be possible to only require 5000 nozzles arranged along the surfaceof the printhead assembly to achieve a desired printing result, whereasfor wider media a minimum of 10,000, 20,000 or 50,000 nozzles may needto be provided along the length of the printhead assembly to achieve thedesired printing result. For full colour photo quality images on A₄ orUS letter sized media at or around 1600 dpi, the integrated circuits 74may have 13824 nozzles per color. Therefore, in the case where theprinthead assembly 22 is capable of printing in 4 colours (C, M, Y, K),the integrated circuits 74 may have around 53396 nozzles disposed alongthe surface thereof. Further, in a case where the printhead assembly 22is capable of printing 6 printing fluids (C, M, Y, K, IR and a fixative)this may result in 82944 nozzles being provided on the surface of theintegrated circuits 74. In all such arrangements, the electronicssupporting each nozzle is the same.

The manner in which the individual ink delivery nozzle arrangements maybe controlled within the printhead assembly 22 will now be describedwith reference to FIGS. 37-46.

FIG. 37 shows an overview of the integrated circuit 74 and itsconnections to the SoPEC device (discussed above) provided within thecontrol electronics of the print engine 1. As discussed above,integrated circuit 74 includes a nozzle core array 901 containing therepeated logic to fire each nozzle, and nozzle control logic 902 togenerate the timing signals to fire the nozzles. The nozzle controllogic 902 receives data from the SoPEC device via a high-speed link.

The nozzle control logic 902 is configured to send serial data to thenozzle array core for printing, via a link 907, which may be in the formof an electrical connector. Status and other operational informationabout the nozzle array core 901 is communicated back to the nozzlecontrol logic 902 via another link 908, which may be also provided onthe electrical connector.

The nozzle array core 901 is shown in more detail in FIGS. 38 and 39. InFIG. 38, it will be seen that the nozzle array core 901 comprises anarray of nozzle columns 911. The array includes a fire/select shiftregister 912 and up to 6 color channels, each of which is represented bya corresponding dot shift register 913.

As shown in FIG. 39, the fire/select shift register 912 includes forwardpath fire shift register 930, a reverse path fire shift register 931 anda select shift register 932. Each dot shift register 913 includes an odddot shift register 933 and an even dot shift register 934. The odd andeven dot shift registers 933 and 934 are connected at one end such thatdata is clocked through the odd shift register 933 in one direction,then through the even shift register 934 in the reverse direction. Theoutput of all but the final even dot shift register is fed to one inputof a multiplexer 935. This input of the multiplexer is selected by asignal (corescan) during post-production testing. In normal operation,the corescan signal selects dot data input Dot[x] supplied to the otherinput of the multiplexer 935. This causes Dot[x] for each color to besupplied to the respective dot shift registers 913.

A single column N will now be described with reference to FIG. 46. Inthe embodiment shown, the column N includes 12 data values, comprisingan odd data value 936 and an even data value 937 for each of the six dotshift registers. Column N also includes an odd fire value 938 from theforward fire shift register 930 and an even fire value 939 from thereverse fire shift register 931, which are supplied as inputs to amultiplexer 940. The output of the multiplexer 940 is controlled by theselect value 941 in the select shift register 932. When the select valueis zero, the odd fire value is output, and when the select value is one,the even fire value is output.

Each of the odd and even data values 936 and 937 is provided as an inputto corresponding odd and even dot latches 942 and 943 respectively.

Each dot latch and its associated data value form a unit cell, such asunit cell 944. A unit cell is shown in more detail in FIG. 46. The dotlatch 942 is a D-type flip-flop that accepts the output of the datavalue 936, which is held by a D-type flip-flop 944 forming an element ofthe odd dot shift register 933. The data input to the flip-flop 944 isprovided from the output of a previous element in the odd dot shiftregister (unless the element under consideration is the first element inthe shift register, in which case its input is the Dot[x] value). Datais clocked from the output of flip-flop 944 into latch 942 upon receiptof a negative pulse provided on LsyncL.

The output of latch 942 is provided as one of the inputs to athree-input AND gate 945. Other inputs to the AND gate 945 are the Frsignal (from the output of multiplexer 940) and a pulse profile signalPr. The firing time of a nozzle is controlled by the pulse profilesignal Pr, and can be, for example, lengthened to take into account alow voltage condition that arises due to low power supply (in aremovable power supply embodiment). This is to ensure that a relativelyconsistent amount of ink is efficiently ejected from each nozzle as itis fired. In the embodiment described, the profile signal Pr is the samefor each dot shift register, which provides a balance betweencomplexity, cost and performance. However, in other embodiments, the Prsignal can be applied globally (ie, is the same for all nozzles), or canbe individually tailored to each unit cell or even to each nozzle.

Once the data is loaded into the latch 942, the fire enable Fr and pulseprofile Pr signals are applied to the AND gate 945, combining to thetrigger the nozzle to eject a dot of ink for each latch 942 thatcontains a logic 1.

The signals for each nozzle channel are summarized in the followingtable:

Name Direction Description D Input Input dot pattern to shift registerbit Q Output Output dot pattern from shift register bit SrClk InputShift register clock in - d is captured on rising edge of this clockLsyncL Input Fire enable - needs to be asserted for nozzle to fire PrInput Profile - needs to be asserted for nozzle to fire

As shown in FIG. 46, the fire signals Fr are routed on a diagonal, toenable firing of one color in the current column, the next color in thefollowing column, and so on. This averages the current demand byspreading it over 6 columns in time-delayed fashion.

The dot latches and the latches forming the various shift registers arefully static in this embodiment, and are CMOS-based. The design andconstruction of latches is well known to those skilled in the art ofintegrated circuit engineering and design, and so will not be describedin detail in this document.

The nozzle speed may be as much as 20 kHz for the printer unit 2 capableof printing at about 60 ppm, and even more for higher speeds. At thisrange of nozzle speeds the amount of ink than can be ejected by theentire printhead assembly 22 is at least 50 million drops per second.However, as the number of nozzles is increased to provide forhigher-speed and higher-quality printing at least 100 million drops persecond, preferably at least 500 million drops per second and morepreferably at least 1 billion drops per second may be delivered. At suchspeeds, the drops of ink are ejected by the nozzles with a maximum dropejection energy of about 250 nanojoules per drop.

Consequently, in order to accommodate printing at these speeds, thecontrol electronics must be able to determine whether a nozzle is toeject a drop of ink at an equivalent rate. In this regard, in someinstances the control electronics must be able to determine whether anozzle ejects a drop of ink at a rate of at least 50 milliondeterminations per second. This may increase to at least 100 milliondeterminations per second or at least 500 million determinations persecond, and in many cases at least 1 billion determinations per secondfor the higher-speed, higher-quality printing applications.

For the printer unit 2 of the present invention, the above-describedranges of the number of nozzles provided on the printhead assembly 22together with the nozzle firing speeds and print speeds results in anarea print speed of at least 50 cm² per second, and depending on theprinting speed, at least 100 cm² per second, preferably at least 200 cm²per second, and more preferably at least 500 cm² per second at thehigher-speeds. Such an arrangement provides a printer unit 2 that iscapable of printing an area of media at speeds not previously attainablewith conventional printer units.

Maintenance Assembly

The maintenance assembly 23 is shown in detail in FIGS. 47-50, and aspreviously shown in FIG. 8, it is mounted between the posts 26 of themain body 20, so as to be positioned adjacent the printhead assembly 22.

The maintenance assembly 23 generally consists of a maintenance chassis88 which receives the various components of the assembly therein. Themaintenance chassis 88 is in the form of an open ended channel having apair of upwardly extending tongue portions 89 at its ends which areshaped to fit over the posts 26 of the main body 20 and engage with theretaining projections provided thereon to secure the maintenanceassembly 23 in position. The maintenance chassis 88 is made from asuitable metal material, having rigidity and resilience, such as apressed steel plate.

The base of the maintenance chassis 88 is shown more clearly in FIG. 49and includes a centrally located removed portion 90, window portions 92and spring arms 91 extending from either side of the window portions 92.The integral spring arms 91 are angled internally of the chassis 88 andformed by pressing the sheet metal of the chassis. Of course the springarms 91 could equally be a separate insert placed into the open channelof the chassis 88.

A rigid insert 93 is provided to fit within the chassis 88 to provideadded rigidity to the maintenance assembly 23. A catch element 94projects from the base of the rigid insert and extends into thecentrally located removed portion 90 of the chassis 88 when the rigidinsert 93 is located within the chassis 88. The catch element 94 isprovided to move the maintenance assembly between a capped and anuncapped state, as will be described below. A lower maintenance molding95 is located within the insert 93 and retained within the insert viaengagement of a number of lugs 96 formed along the sides of the lowermaintenance molding 95 with corresponding slots 97 provided along thesides of the insert 93. The lower maintenance molding 95 is made from asuitable plastic material and forms a body having closed ends and anopen top. The ends of the lower maintenance molding 93 are provided withair vents 98. Air from the vents 98 flows through filters 181 toventilate the maintenance assembly.

Two pin elements 99 extend from the base of the lower maintenancemolding 95. The pin elements 99 are connected to the base via a flexibleweb, such as rubber, to allow multi-directional relative movement of thepin elements 99 with respect to the base of the lower maintenancemolding. The pin elements 99 pass through two circular openings 100 inthe base of the rigid insert 93 and into the window portions 92 of themaintenance chassis 88.

A retainer insert 101 is supported on the pin elements 99 within thelower maintenance molding 95. The retainer insert 101 is coated steeland provides rigid support for the strips of absorbent media 102retained therein. The absorbent media 102 is a generally an invertedT-shaped assembly of separate portions—a thin vertical portion whichextends upwardly from between two substantially horizontal portions. Theabsorbent media 102 may be made from any type of material capable ofabsorbing and retaining ink such as urethane foam or the like.

A microfibre fabric 103 fits over the thin vertical portion, around thetwo horizontal portions, and then attaches to the retainer insert 101 toretain the absorbent media 102. The microfibre fabric 103 draws into theabsorbent media 102.

An upper maintenance molding 104 fits over the lower maintenance molding95 to enclose the microfibre fabric 103, absorbent media 102 andretainer insert 101 therebetween. The upper maintenance molding 104 isattached along its bottom surface to the surface of the lowermaintenance molding 95 via an appropriate adhesive. An upwardlyprojecting rim portion 105 extends beyond the thin vertical portion ofthe absorbent media 102 covered with microfibre fabric 103. The rimportion 105 defines an open perimeter seal for sealing the nozzles ofthe printhead assembly 22 when the upper maintenance molding 104 isbrought into capping contact with the printhead assembly.

In this arrangement, the upper maintenance molding 104, microfibrefabric 103, absorbent media 102, retainer insert 101, lower maintenancemolding 95 and the rigid insert 93 form a capping unit which is adaptedto fit within the maintenance chassis 88 and is supported on the springarms thereof. Within this unit, the microfibre fabric 103, absorbentmedia 102 and the retainer insert 101 form a sub-unit supported on thepin elements 99 and movable within the space defined by the lowermaintenance molding 95 and the upper maintenance molding 104.

As shown in FIG. 47, the capping unit is held in place with a retainerelement 106 that fits over the upper maintenance molding 104 and securesto the chassis 88. The retainer element 106 is essentially in the formof an open ended channel having a slot 107 formed along the uppersurface thereof, through which the rim portion 105 of the uppermaintenance molding 104 can protrude and cappingly engage with theprinthead assembly 22. The upper surface of the retainer element 106 iscurved and acts as a media guide during printing.

When assembled in this manner, the components of the maintenanceassembly 23 are contained within the retainer element 106 and thechassis 88, such that both the upper maintenance molding 104 can movewith respect to the retainer element 106 to cap the printhead assembly22, and the microfibre fabric 103 and absorbent media 102 can move withrespect to the upper maintenance molding to contact and wipe the surfaceof the nozzles of the printhead assembly 22.

Upon assembly and attachment of the maintenance assembly 23 to the posts26 of the main body 20, the catch element 94 of the rigid insert extendsfrom the central removed portion 90 of the chassis 88. Due to the actionof the spring arms 91, the maintenance unit 23 (as previously defined)is raised from the base of the chassis 88 such that the rim portion 105of the upper maintenance molding 104 extends through the slot 107 of theretainer element 106 and is in capping contact with the printheadassembly 22. This state is shown in FIG. 50 and is referred to as thecapping state, whereby the nozzles of the printhead are sealed in analmost closed environment within the rim portion 105 and are less likelyto dry out and clog with ink. The environment is almost closed and notfully closed, so that the maintenance assembly is not prevented frommoving to the uncapped state because of a mild vacuum created within therim 105.

To remove any paper dust or other particulate matter present in thevicinity of the nozzles of the printhead assembly 22, the surface of theprinthead may be wiped by the microfibre fabric 103. To perform this, awiper actuator present in the cradle unit extends into the windowportions 92 of the chassis 88 and contacts the pin elements 99 providedin the base of the lower maintenance molding 95. Any upward forceprovided by the wiper actuator on the pins 99 causes them to projectfurther against the retainer insert 101, thereby causing the verticalportion of the absorbent media 102, which is coated with the microfibrefabric 103, to extend into and beyond the rim portion 105 of the uppermaintenance molding 104, until it contacts the surface of the printheadassembly 22 proximal the nozzles. The presence of the microfibre fabric103 ensures that contact is minimised and attracts any ink or moisturepresent on the surface of the printhead assembly 22 to be retainedwithin the absorbent media 102. As the pins 99 are free to move in anydirection, any lateral motion of the wiper actuator will cause themicrofibre fabric 103 to move laterally across the surface of thenozzles hence performing a wiping or cleaning function. Removal of thewiper actuator will then cause the arrangement to return to a positionwhereby the microfibre fabric 103 and the absorbent media 102 are belowthe surface of the rim portion 105.

In order to perform printing, the maintenance assembly 23 must be movedfrom the capping state to a printing state. This is achieved by amaintenance actuator gripping the catch element 94 projecting throughthe central removed portion 90 of the chassis 88 and applying a downwardforce thereto. This downward force causes the rigid insert 93 to moveagainst the spring arms 91 of the chassis 88, towards the base of thechassis. This movement causes the upper rim portion 105 of the uppercapping molding 104 to retract into the slot 107 formed in the retainerelement 106 such that it is flush with the outer surface of the retainerelement 106 and does not protrude therefrom. It will be appreciated thatthe retainer element 106 does not move and is fixed in position. Thiscreates a gap between the retainer element 106 and the printheadassembly 22 through which the media can pass for printing. In theprinting or uncapped state, the retainer element 106 acts as a mediaguide and the media contacts the retainer element and is supported onthe surface of the retainer element 106 as it passes the printheadassembly for printing.

Cradle Unit

The cradle unit 12 is shown in relation to FIGS. 6 and 7 and generallyconsists of a main body 13 which defines an opening 14 for receiving thecartridge unit 10, and a cover assembly 11 adapted to close the openingto secure the cartridge unit 10 in place within the cradle unit 12.

The main body 13 of the cradle unit 12 includes a frame structure 110 asshown in FIGS. 51A and 51B. The frame structure 110 generally comprisestwo end plates 111 and a base plate 112 connecting each of the endplates 111. A drive roller 113 and an exit roller 114 are mountedbetween the end plates 111 at opposing ends thereof, such that when thecartridge unit 10 is retained within the main body 13, it sets betweenthe drive roller 113 and exit roller 114. The drive roller 113 and theexit roller 114 are each driven by a brushless DC motor 115 which ismounted to one of the end plates 111 and drives each of the drive andexit rollers via a drive mechanism 116, such as a drive belt. Such asystem ensures that both the drive roller 113 and the exit roller 114are driven at the same speed to ensure a smooth and consistent passageof the media through the print engine 1 and past the printhead assembly22 of the cartridge unit 10.

A maintenance drive assembly 117 is mounted to the other end plate 111,opposite the DC motor 107. The maintenance drive assembly 117 comprisesa motor 118 which is operatively connected to a maintenance gear 119 anda wiper gear 120. The maintenance gear 119 is in turn connected to amaintenance actuator 121 which is in the form of a rod having a hookedend that extends a distance within the base plate 112. The hooked end ofthe maintenance actuator 121 is shaped to be received within the catchelement 94 of the maintenance assembly 23 so as to raise/lower the upperrim portion 105 between the capping state and the printing state. Thewiper gear 120 is similarly connected to a wiper actuator 122 in theform of a rod having a pair of projections extending therefrom. Thewiper actuator 122 similarly extends within the base plate 112, and theprojections are positioned along the wiper actuator 122 so that they arealigned with the window portions 92 formed in the base of themaintenance chassis 88 so as to contact the pin elements 99 of themaintenance assembly 23.

The maintenance drive assembly 117 is shown in isolation in FIGS. 52Aand 52B. As the motor 118 is bi-directional, operation of the motor inone direction will cause the wiper gear 120 to move in acounter-clockwise direction as shown in FIG. 52A. The wiper gear 120,has a raised portion 123 formed on the surface thereof which comes intocontact with an arm 124 of the wiper actuator as the wiper gear 120rotates. As the raised portion 123 contacts the arm 124, the wiperactuator 122 pivots such that the projections formed thereon move in anupward direction through the window portions 92 in the maintenancechassis 88 and against the pin elements 99, thereby bring the microfibre fabric 103 against the surface of the printhead assembly. Furtherrotation of the wiper gear 120 will result in the arm 124 returning toits neutral position. Lateral movement can be applied to the wiperactuator 122 due to the presence of an additional angled raised portion125 formed on the wiper gear 120 upon which the arm 124 rides causes theentire wiper actuator to move laterally against the returning spring126. A sensor element 127 is provided to sense the position of the wiperactuator such that the state of the printhead can be readily determined.

In order to control the capping state of the printhead assembly 22, themotor 118 is reversed resulting in the wiper gear 120 moving in aclockwise direction as shown in FIG. 52A and a counter-clockwisedirection as shown in FIG. 52B. Rotation of the wiper gear 120 in thisdirection ensures that the wiper actuator pivots in a downward directionaway from the maintenance assembly 23. However as shown more clearly inFIG. 52B, this rotation causes a flipper gear 128 provided on the innersurface of the wiper gear 120 to engage with the maintenance gear 119and in turn cause the maintenance gear 119 to rotate in a counterclockwise direction (as shown in FIG. 52B). Similarly, a projection 129formed on the inner surface of the maintenance gear 119 contacts a pivotarm 130 of the maintenance actuator 121, thereby causing the hooked endof the maintenance actuator to move in a downward direction, which inturn grips the catch element 94 of the maintenance assembly 23 causingthe upper rim portion 105 to retract and assume a printing state.Similarly, the sensor element 127 can sense the position of themaintenance actuator to control operation of the motor 118, and hencethe desired state of the printhead.

Referring again to FIGS. 51A and 51B, a pair of cartridge unit guides131 are attached to the end plates 111 to aid in receiving and guidingthe cartridge unit 10 into the cradle unit 12. The guides 131 are angledto receive a surface of the cartridge unit 10 such that the cartridgeunit 10 is orientated correctly with respect to the cradle unit 12.

The control electronics for controlling the operation of the printengine and the ICs 50 of the printhead assembly 22 is provided on aprinted circuit board (PCB) 132. As shown in FIG. 51A, one face of thePCB 132 contains the SoPEC devices 133 and related componentry 134 forreceiving and distributing the data and power received from externalsources, whilst the other face of the PCB includes rows of electricalcontacts 135 along a lower edge thereof which provides a means fortransmitting the power and data signals to the corresponding electricalcontacts on the flex PCB 79 for controlling the nozzles of the printheadassembly 22.

As shown in isolation in FIG. 53, the PCB 132 forms part of a PCBassembly 140, and is mounted between two arms 136, with each of the armshaving a claw portion 137 to receive and retain the PCB 132 in position.As shown in FIG. 54, each of the arms 136 has a groove 141 formed in theupper portion thereof for receiving a hook portion of a tension spring142, the purpose of which will be described below.

In order to provide stability to the PCB 132 as it is mounted betweenthe two arms 136, a support bar 138 is secured to the arms 136 and thePCB along the bottom edge of the PCB 132, on the face that contains theSoPEC devices 133 and the related componentry 134. The support bar 138has a plurality of star wheels 139 mounted along its lower surface. Thestar wheels are spring loaded such that they can move relative to thelower surface of the support bar to grip with a surface of the exitroller 114 when the PCB assembly 140 is mounted to the end plates 111,as shown in FIG. 51A.

A heatshield 143 is attached to the PCB 132, as shown in FIG. 55A suchthat it substantially covers the SoPEC devices 133 and protects theSoPEC devices from any EMI that may be within the vicinity of theprinter unit 2. The heatshield 143 also has a latch mechanism 144provided therein which mates with a clip provided on the cover assembly11 to secure the cover assembly in a closed position as shown in FIG.55A.

The PCB assembly 140 is pivotally mounted to the end plates 111 at pivotpoints 141 provided at the bottom of the arms 136. In this arrangement,the PCB assembly 140 is able to swing about its pivot points 141 betweenan open position, wherein the electrical contacts 135 are remote fromthe electrical contacts of the flex PCB 79 and the cartridge unit 10 canbe readily removed from the cradle unit 12, and a closed position, wherethe electrical contacts 135 are in operational contact with theelectrical contacts provided on the flex PCB 79 to transmit control dataand power to facilitate printing from the nozzles of the printheadassembly 22.

As shown in FIG. 55B, an idle roller assembly 145 is secured to the endplates 111 at the rear of the cradle unit 12 and includes a plurality ofroller wheels 152 which are positioned to contact the surface of thedrive roller 113 and rotate therewith. The idle roller assembly 145ensures that any media that is presented to the print engine 1 from thepicker mechanism 9 of the printer unit 2, is gripped between the driveroller 113 and the roller wheels 146 of the idle roller assembly 1145for transport past the printhead assembly 22 of the cartridge unit 10for printing.

The cover assembly 11, is shown in its closed position in FIGS. 55A and55B, and is pivotally attached to the end plates 111 at an upper rearportion thereof. A pair of attachment plates 147 extend from the coverassembly 11 for attaching the cover assembly to the end plates 111 via apin 148. The attachment plates 147 extend beyond the pin 148 and have ahole formed therein into which is received the free end of the tensionspring 142 as discussed previously in relation to FIG. 54.

When the cover assembly 11 is in the closed position, as shown in FIG.55B, the spring is in full tension which in turn causes the PCB assembly40 to pivot towards the closed position, as shown in cross-section inFIG. 56A. In this position, the electrical contacts 135 of the PCB 132are in operational contact with the corresponding electrical contacts ofthe flex PCB 79 of the printhead assembly 22 such that power and datasignals can be transferred therebetween.

When the cover assembly is moved to its open position, as shown in FIG.55C, the attachment plates 147 pivot towards the front of the cradleassembly thereby relieving tension in the spring 142 and causing thespring to become slack. This in turn, allows the PCB assembly to pivotaway into an open position as shown in FIG. 56B. In this position, theelectrical contacts 135 of the PCB 132 move away from contacting thecorresponding contacts of the flex PCB 79 of the printhead assembly 22,to thereby enable the cartridge unit 10 to be removed from the cradleunit 12.

In this regard, the act of opening/closing the cover assembly 11 alsoperforms the function of disengaging/engaging electrical communicationbetween the cartridge unit 10 and the cradle unit 12.

Referring again to FIGS. 55A-55C, the cover assembly 11 includes anumber of docking ports 149 formed in the upper surface thereof. In theembodiment shown there are five docking ports 149 provided, with eachdocking port corresponding to one of the ink storage modules 45. Eachdocking port 149 has an upwardly projecting lip portion which is shapedto receive an ink refill unit for supplying refill ink to the inkstorage modules 45. As more clearly shown in FIG. 55C, each docking port149 has a large, substantially circular opening 151 and two smallcircular openings 152 provided therein, which enable the delivery of inkbetween the ink refill unit and the cartridge unit 10 to occur in themanner as described below.

Four T-shaped openings 182 are positioned at the corners of each dockingportion 149 to receive the bag constrictor actuators on the refill.These were briefly discussed above in relation to the ink storagemodules 45 and are described in more detail below.

Refill Unit

FIGS. 57A-57C show the ink refill unit 155 for supplying refill ink tothe cartridge unit 10. The ink refill unit 155 is provided as a unitcomprising a base assembly 156 which houses internal ink refillingcomponents and a cover 157 which fits over the base assembly 156. Thebase assembly and cover may be moulded from a plastics material and thebase assembly 156 may be moulded as a single piece or in sections.

The underside of the base assembly 156 is shown in more detail in FIG.57B and includes a ridge portion 160 that projects therefrom and whichmates with docking port 149 formed in the cover assembly 11, to retainthe ink refill unit in docking position. A substantially cylindrical inkoutlet 158 also projects from the underside of the base assembly fordelivering ink into the cartridge unit 10. A two valve actuating pins159 also project from the underside of the base assembly 156 foractuating the inlet and outlet valves of the ink storage modules 45respectively. In the embodiment shown, the two valve actuating pins 159have a tri star cross section for good unidirectional bending resistanceand buckling strength. A QA chip 161 is also provided to project fromthe underside of the base assembly 156 and has a plurality of QA chipcontacts 162 exposed thereon which are read by a QA chip reader providedin the cover assembly 11 when the ink refill unit 155 is dockedtherewith.

A constrictor actuator 190 projects from adjacent each corner of thebase assembly 156. The constrictor actuators 190 are slightly arcuateand rounded at their ends. The constrictor apertures 60 (see FIG. 14) inthe top 42 of the cartridge unit 10, are correspondingly arcuate. Therounded ends and arcuate cross section allow the user to easily alignone constrictor actuator 190 with its corresponding aperture 60, and thecurved surfaces intuitively guide the other constrictor actuators 190into alignment with their respective apertures 60. This helps to dockthe refill unit with the interface 61 quickly and with minimal finepositioning by the user. As best shown in FIG. 57B, each constrictoractuator 190 has a buttress reinforcement 191. This gives theconstrictor actuators 190 a high bending strength in order to withstandlarge lateral forces in the event that users apply excessive force whenaligning the refill unit with the docking port.

As described above with reference to FIG. 12, the constrictor actuators190 actuate the bag constrictor 43 of the ink storage module 45.

The base assembly 156 also has a filling port 192. The bag 163 receivesits initial charge of ink through this port which is then sealed with aplastic sealing ball 193.

Referring to the exploded view of FIG. 57C, an ink bag 163 is sealed tothe inner surface of the base assembly 156 for storing the refill inktherein, and is made from a deformable material which allows the ink bag163 to expand/collapse as ink is supplied to/removed from the ink refillunit 155. An ink delivery needle 164 extends into the space providedbetween the bag 163 and the base assembly 156 and provides a passage forink to flow to the outlet 158. The end of the ink delivery needle 164extends into the cylindrical outlet 158, and is surrounded by a sealring 165 which is spring loaded via a compression spring 166 within theopen end of the cylindrical outlet 158. When the ink refill unit 155 isnot docked with the cartridge unit 10, the delivery needle is protectedby the seal ring 165. As a further precaution, a plastic cap 187 is slidover the outlet and held in place by a slight interference fit.

An ink level indicator 167 is also provided within the cover 157 of theink refill unit 155. The ink level indicator 167 comprises a flexiblestrip having an indication portion 168, such as a coloured section. Thestrip is attached to the upper surface of the deformable ink bag 163 atits ends and to the underside of the cover 157 at its centre, so thatwhen the ink supply within the bag 163 is exhausted, i.e., the bag issubstantially empty, the indication portion 168 aligns itself with atransparent window 169 provided in the top surface of the cover 157. Inthis regard, at any other time, i.e., when the bag is other thansubstantially empty, the indication portion is hidden from view.

As the ink dispenses, the nature of the ink bag material causes it todeform and collapse in a non-uniform manner. Each of the edges of theupper surface of the bag are unlikely to collapse at the same rate. Assuch, the length of the ink level indicator 167 is ensures that theindication portion 168 only aligns with the window 169 in the cover 157once all of the edges of the deformable bag's upper surface have fullycollapsed. In this regard, the ink level indicator strip 182 isinitially in a folded state with the indication portion 168 beinglocated on the strip 182 so as to be hidden from the window 169 when thebag 163 is full. The strip 167 is attached at either end to oppositeedges of the bag's upper surface. A point (not shown) intermediate theends is secured beneath the transparent window 169. When the bag 46fully collapses the strip 167 lengthens and unfolds. This brings thepreviously hidden indication portion 168 into view through the window169. The use of the ink level indicator 167 means that the one refillunit 155 can be used for multiple refill operations if the refill unitis not fully exhausted. This may occur when the amount of ink necessaryfor refilling the corresponding ink storage module 45 of the cartridgeunit 10 in one operation is less than the capacity of the refill unit.

The cover 157 fits over a portion of the base assembly 156 to enclosethe ink bag 163 and ink level indicator 167. Likewise, U-shaped dockingclasp 183 fits over the cover 157 such that its legs extend beyond thebase assembly 156 to engage the cartridge unit 10 when docked. Clips 170on opposing legs of the clasp 183 snap lock onto the sides of thecartridge unit 10. This holds the refill unit 155 substantially fixedrelative the cover assembly 11 for reliable and efficient transfer ofink.

An opposing pair of leaf springs 184 extend from inside each leg of theU-shaped clasp to press against the sides of the cover 157. Adjacenteach leaf spring is a pivot 185 designed to engage a fulcrum ledge 186on the side of the cover 157. This pushes the legs outwardly, however asthe pivot 185 engages the fulcrum 186, the clips are levered inwardly tomaintain engagement with the cartridge unit 10.

A label panel 188 is fixed to the outer surface of the clasp 183. Thelabel panel 188 can display trademark and other information. It may alsobe coloured to match the ink within the refill. The label panel 188 alsohas finger grip pads 189 on each leg. The finger grip pads 189 arepositioned so that finger pressure at these points will overcome theforce of the leaf springs 184 to lever the clips 170 out of engagementwith cartridge unit 10. The refill unit 155 may then be pulled off thedocking port 149 of the cover assembly 11.

FIG. 58 shows the refill unit 155 docked directly with one of theinterfaces 61 of the ink storage module assembly 11 of the cartridgeunit 10. The cover assembly 11 and remainder of the cradle unit havebeen removed for clarity. The refill unit 155 is shaped, or ‘keyed’,such that it can only be received within the docking port 149 in oneparticular orientation. The ends of each leg of the U-shapes clasp 183are significantly different widths so that the user is less likelyattempt to dock the unit 155 back-to-front. The cylindrical ink outlet158 is offset from the lateral centre line to also guard againstback-to-front docking of the refill unit 155. As previously discussed,the base of the docking port 149 has a large circular opening 151, intowhich is received the cylindrical ink outlet 158, and two smalleropenings 152, into which the valve actuators 159 are received. The crosssections of each of these interacting elements are shaped so that onlythe correctly coloured ink refill unit, in the correct orientation, canbe used to refill each particular ink storage module 45. For example,the two tri star cross sections of the valve actuators 159 can each berotated to give a large number of combinations that will only mate withcorresponding tri star apertures, each with a matching rotationalorientation.

A QA chip reader 172 is also provided in the base of the docking port149 for mating with the QA chip contacts 162 of the QA chip 161 of therefill unit 155 and reading and receiving information stored thereon.Such information may include the storage capacity of the refill unit 155(e.g., about 30 to about 50 ml), the colour of the ink contained withinthe refill unit 155, and the source of the ink contained within the inkrefill unit 155. The information can be readily transferred to thecontrol circuitry of the cradle unit 12 when the refill unit 155 isdocked into position within the docking port 149. For example, thecontrol circuitry of the cradle unit 12 is able to determine which ofthe ink storage modules 45 require refilling and whether the refill unit155 contains the correct type/colour and amount of ink to facilitaterefilling.

As shown more clearly in FIG. 59, the valve insert 49 of each of the inkstorage modules 45 (see FIG. 10) is arranged such that the ink inlet 15is aligned with the large circular opening 151 formed in the dockingport 149, and the ink inlet and outlet valves 16 and 18 respectively,are aligned with the tri star openings 152. As the ink refill unit 155is brought into position within the docking port 149, the ink outlet 158of the refill unit 155 contacts the ink inlet 15 of the ink storageassembly 45, and the valve actuator pins 159 contact each of the inkinlet valve 16 and ink outlet valve 18.

In this position, the ink delivery needle 164 penetrates the ink inlet15 of the valve insert 49 as the spring loaded seal ring 165 retractswithin the cylindrical ink outlet 158 to form a tight seal around thesurface of the ink inlet 15. The seal ring 165 is able to ‘ride’ up theink delivery needle 164 and is loaded such that upon removal of therefill unit 155 from the docking port 149, the seal ring is returned toits protection position via action of a seal spring 166.

As discussed previously, the ink retained within ink bag 46 of the inkstorage module 45 is in a constant state of negative pressure due to thespring element 54 applying a constant expansion force to the ink bag 46.This produces a negative or back pressure in the ink, thereby preventingink from leaking from the nozzles of the printhead assembly 22. Thisback pressure also provides a simple means for extracting the refill inkfrom the refill unit 155 when the refill unit is docked into position.Due to a pressure gradient between the ink bag of the refill unit 155(which is at atmospheric pressure) and the ink bag of the ink storagemodule 45, when the ink delivery needle 164 penetrates the ink inlet 15,the refill ink simply flows from the refill unit 155 into the ink bag 46of the ink storage module 45.

In order to alternate between a refilling operation and a printingoperation and to maintain the ink in the printhead assembly 22 in aconstant state of back pressure such that ink does not leak from thenozzles during refilling, valves 16 and 18 are provided in the valveinsert as discussed above. Both valves are controlled by the valveactuator pins 159 when the refill unit is docked into position with thedocking port 149. The manner in which the valves are controlled is shownwith reference to FIGS. 60A-60D.

FIGS. 60A and 60B show different cross-sectional views respectivelyalong lines A-A and B-B in FIG. 59 illustrating a state of the valvearrangement before refilling, and FIGS. 60C and 60D respectively showthe views of FIGS. 60A and 60B illustrating a state of the valvearrangement during refilling.

Prior to refilling, as shown in FIGS. 60A and 60B, the ink inlet valve16 is in a closed position, thereby preventing the passage of ink or airfrom entering the ink inlet 15 and making its way into the ink bag 46.This is shown in FIG. 60B, whereby any ink present in the passagebetween the ink inlet 15 and the ink inlet valve 16 remains in thisspace. An o-ring seal is provided at the ink inlet 15 to maintain an airtight seal around the ink delivery needle 164 of the refill unit 155. Inthis state, the ink outlet valve 18 is in an open position therebyproviding a passage for ink to flow out the ink outlet 52, down the inkdownpipe 30 and to the printhead assembly 22. As discussed, the springelement 54 establishes a state of back pressure within the ink bag 46,and the printhead 22 draws the ink from the ink bag 46 against this backpressure during printing.

During refilling, as shown in FIGS. 60C and 60D, the ink refill unit 155is docked into the docking port 149 such that the ink outlet 158 engageswith the ink inlet 15 of the valve insert 49 and the valve actuator pins159 come into engagement with the valves 16 and 18. As shown in FIG.60C, contact of the valve actuator pin with the ink outlet valve 18causes the valve 18 to be depressed and close, thereby preventingfurther ink flow from the ink outlet 52 to the printhead assembly 22. Inthis regard, ink present in the passage from the closed ink outlet valve18 to the printhead assembly 22 remains stationary until the ink outletvalve 18 opens.

As shown more clearly in FIG. 60D, when the valve actuator pin 159contacts the ink inlet valve 16 and depresses the valve, the valve opensallowing a passage for the ink to flow from the refill unit 155 to theink bag 46. Due to the back pressure present in the ink bag 46, the inkis drawn into the ink bag due to the pressure differential and as theink bag 46 fills and expands with ink, the spring element 54 maintains aconstant force between the ink bag 46 and the retainer element 55,thereby also maintaining a constant back pressure within the ink in theink bag 46. This continues until the ink bag 46 reaches its maximumcapacity whereby the pressure of the ink present in the ink bag 46equalises with the pressure of the ink of the refill unit 155 and nomore ink is drawn from the refill unit 155.

Bag constrictor actuators 190 extend through the apertures 60 to pressthe upper constrictor collar 59 towards the lower constrictor collar 57to bow the side panels 58 inwards and constrict the bag 46. As discussedabove with reference to FIG. 12, the bag constrictor 43, re-establishesthe negative pressure in the ink bag 46 as the refill unit is removed,by releasing the constriction.

While the present invention has been illustrated and described withreference to exemplary embodiments thereof, various modifications willbe apparent to and might readily be made by those skilled in the artwithout departing from the scope and spirit of the present invention.Accordingly, it is not intended that the scope of the claims appendedhereto be limited to the description as set forth herein, but, rather,that the claims be broadly construed.

1. A micro-systems technology (MST) device for attachment to an adhesivesurface, the MST device comprising: an attachment surface for abuttingthe adhesive surface; a plurality of first fluid conduits connected toan array of inlet apertures in the attachment surface; and, an array ofrecesses interspersed with the array of inlet apertures to hold adhesivedisplaced from between the attachment surface and the adhesive surfacewhen the MST device is attached such that displaced adhesive does notblock fluid flow into the first fluid conduits.
 2. A micro-systemstechnology (MST) device according to claim 1 wherein the array of inletapertures is series of open channels in the attachment surface.
 3. Amicro-systems technology (MST) device according to claim 2 wherein thearray of recesses is an arrangement of pits in the attachment surface.4. A micro-systems technology (MST) device according to claim 3 whereinthe channels are more than 50 microns wide and each separated by morethan 50 microns of the attachment face.
 5. A micro-systems technology(MST) device according to claim 4 wherein the channels are about 80microns wide and separated by about 80 microns of attachment surface. 6.A micro-systems technology (MST) device according to claim 5 wherein thepits are more than 5 microns wide and more than 5 microns deep.
 7. Amicro-systems technology (MST) device according to claim 6 wherein theadhesive is a thermosetting adhesive that cures at a predeterminedtemperature.
 8. micro-systems technology (MST) device according to claim7 wherein the thermosetting adhesive has a maximum curing temperature of150 degrees Celsius.
 9. A micro-systems technology (MST) deviceaccording to claim 8 wherein the thermosetting adhesive is more than 12microns thick.
 10. A micro-systems technology (MST) device according toclaim 1 wherein the MST device is a printhead IC and the adhesivesurface is on a liquid crystal polymer (LCP) moulding which acts as asupport structure for mounting the printhead IC within an inkjetprinter.